DEPARTMENT OF HEALTH AND HUMAN SERVICES 

CENTERS FOR DISEASE CONTROL AND PREVENTION 

Advisory Committee on 

Immunization Practices (ACIP)

Summary Report

February 26-27, 2020

Atlanta, Georgia 
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

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Table of Contents Page

Agenda 4-5 

Acronyms 6-11

Wednesday: February 26, 2020

Welcome and Introductions 12-14

Ebola Vaccine

 Introduction

 Review of Ebola Virus Disease and rVSVΔG-ZEBOV-GP Vaccine GRADE

 EtR and Summary of Work Group Considerations and Proposed Policy Options

 Vote

14-49

2019 Novel Coronavirus (2019-nCov) Informational Session 49-55

Influenza Vaccines

 Introduction

 Older Adult (65+) Adjuvanted Quadrivalent Influenza Vaccine (aIIV4)

 2019-20 US Influenza Surveillance Update

 2019-20 US Influenza Vaccine Effectiveness Update

 Safety of Adjuvanted vs. High-Dose Inactivated Influenza Vaccines in Older Adults

 Summary and Work Group Considerations

‘ 

56-72

Thursday: February 27, 2020

Agency Updates

 Centers for Disease Control and Prevention (CDC)

 Center for Medicare and Medicaid Services (CMS)

 Department of Defense (DoD)

 Department of Veteran’s Affairs (DVA)

 Food and Drug Administration (FDA)

 Heath Resources and Services Administration (HRSA)

 Indian Health Services (I HS)

 National Institutes of Health (NIH)

 Office of Infectious Disease Policy and HIV/AIDS (OIDP)

o National Vaccine Advisory Committee (NVAC)

o National Vaccine Program Office (NVPO)

73-77

Rabies Vaccine

 Introduction

 Background on PrEP, Vaccine Safety, and Work Group Considerations

 Rabies Vaccine Schedule & Duration of Immunity (Systematic Review Data)

 Work Group Next Steps

78-96 
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Dengue Virus Vaccines

 Introduction

 Dengue Vaccine Acceptability in Puerto Rico

 SAGE Perspective on DENGVAXIA®

 Summary of Work Group Considerations

96-111 

Polio Informational Session

 Introduction

 Polio and Polio Policy in the United States: The Oral Polio Vaccine to Inactivated Vaccine Switch

 Global Polio Eradication: Progress and Prospects

112-123

Hepatitis B Vaccine

 Work Group Updated

123-124

General Best Practices

 Introduction

 Update on Recent Postings

124-126

Vaccine Supply 127

Certification 128

Membership Roster 129-137
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Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

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Acronyms

AAFP American Academy of Family Physicians 

AAP American Academy of Pediatrics

ACCV Advisory Commission on Childhood Vaccines 

ACHA American College Health Association 

ACIP Advisory Committee on Immunization Practices

ACOG American College of Obstetricians and Gynecologists

ACP American College of Physicians 

ACS American Cancer Society

AE Adverse Event

AECI Adverse Events of Clinical Interest 

AESI Adverse Events of Special Interest 

AFM Acute Flaccid Myelitis 

AFRO Africa Regional Office 

AHIP America’s Health Insurance Plans

AI/AN American Indian/Alaskan Native 

aIIV Adjuvanted Inactivated Influenza Vaccine

AIM Association of Immunization Managers 

AIRA American Immunization Registry Association 

AMA American Medical Association

AMGA American Medical Group Association 

AOA American Osteopathic Association 

APhA American Pharmacists Association 

APHL Association of Public Health Laboratories 

AS American Samoa

ASH Assistant Secretary for Health 

ASPR Assistant Secretary for Preparedness and Response 

ASTHO Association of State and Territorial Health Officers 

ATS American Thoracic Society 

BLA Biologics License Application

BSC, DDID Board of Scientific Counselors, Deputy Director for Infectious Diseases 

BSL-4 Biosafety Level 4 

CBER Center for Biologics Evaluation and Research 

ccIIV Cell Culture-Based Inactivated Influenza Vaccine

CDC Centers for Disease Control and Prevention

CEA Cost-Effectiveness Analysis 

CHMP Committee for Medicinal Products for Human Use 

CICP Countermeasures Injury Compensation Program 

CISA Clinical Immunization Safety Assessment 

CLD Chronic Liver Disease 

CLIA Clinical Laboratory Improvement Amendments 

CMS Center for Medicare and Medicaid Services

CNS Central Nervous System

COI Conflict of Interest 

COPA Communities Organized to Prevent Arboviruses 

COVID-19 Coronavirus Disease 2019 

CSF Cerebrospinal Fluid

CSTE Council of State and Territorial Epidemiologists 
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cVDPV2 Circulating Vaccine-Derived Poliovirus

DC District of Columbia

DENV Dengue Virus 

DFO Designated Federal Official

DNA Deoxyribonucleic Acid 

DoD Department of Defense

DRC Democratic Republic of Congo 

DSMB Data Safety Monitoring Board 

DSTDP Division of STD Prevention 

DTaP Diphtheria and Tetanus Toxoid and Pertussis 

DVA Department of Veterans Affairs

DVD Division of Viral Diseases 

ED Emergency Department

EHR Electronic Health Record 

EIS Epidemic Intelligence Service

ELISA Enzyme-Linked Immunosorbent Assay 

EMA European Medicines Agency 

EMP Essential Medicine Department 

EMR Electronic Medical Record 

EMRO Eastern Mediterranean Region Office 

EQ-5D-5L EuroQOL-5 Dimensions-5 Levels 

EQ-VAS EuroQol-Visual Analogue Scale 

ETC Ebola Treatment Center

EtR Evidence to Recommendation 

EU European Union 

EUA Emergency Use Authorization 

EUL Emergency Use Listing 

EURO Europe Regional Office 

EV Enteroviruses 

EVD Ebola Virus Disease 

FDA Food and Drug Administration

FQHC Federally Qualified Health Center 

FY Fiscal Year 

GAVI Global Alliance for Vaccines and Immunisation; The Vaccine Alliance

GBS Guillain-Barré Syndrome 

GCC Global Certification Commission 

GCC (Tom Harkin) Global Communications Center

GI Gastrointestinal 

GID Global Immunization Division

GISRS Global Influenza Surveillance and Response System 

GMC Geometric Mean Concentration

GMT Geometric Mean Titers 

GP Glycoprotein 

GPEI Global Polio Eradication Initiative 

GRADE Grading of Recommendation Assessment, Development and Evaluation 

GSK GlaxoSmithKline 

HAV Hepatitis A Virus

HBIG Hepatitis B Immune Globulin

HCoVs Human Coronaviruses 
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HCP Healthcare Personnel / Providers

HCW Healthcare Workers 

HDCV Human Diploid Cell Vaccine 

HD-IIV High-Dose Inactivated Influenza Vaccine

HepA Hepatitis A 

HepB Hepatitis B 

HHS (Department of) Health and Human Services

HI Hemagglutinin Inhibition 

HIV Human Immunodeficiency Virus 

HMO Health Maintenance Organization

HPV Human Papillomavirus

HRQOL Health-Related Quality of Life 

HRSA Health Resources and Services Administration 

ICD International Classification of Diseases 

IDCRP Infectious Disease Clinical Research Program 

ICU Intensive Care Unit

ID Intradermal

IDSA Infectious Disease Society of America 

Ig Immunoglobulin

IHB Immunization Healthcare Branch 

IHD Immunization Healthcare Division (DoD)

IHR International Health Regulation

IHS Indian Health Service 

IIS Immunization Information Systems 

IIV Inactivated Influenza Vaccine 

ILI Influenza-Like Illness 

ILINet Influenza-like Illness Surveillance Network 

IM Intramuscular 

IPV Inactivated Polio Vaccine 

ISD Immunization Services Division 

ISO Immunization Safety Office

ISTM International Society for Travel Medicine 

IVIG Intravenous Immunoglobulin 

KPSC Kaiser Permanent Southern California 

LAIV Live Attenuated Influenza Vaccine

LRN Laboratory Response Network 

MASO Management Analysis and Services Office 

MedDRA Medical Dictionary for Regulatory Activities 

MERS Middle East Respiratory Syndrome

MHS Military Health System

MMR Measles, Mumps, and Rubella 

MMWR Morbidity and Mortality Weekly Report

mOPV Monovalent OPV 

MSM Men Who Have Sex With Men 

MI Multiple Imputation 

NACCHO National Association of County and City Health Officials 

NACI National Advisory Committee on Immunization Canada

NAIP National Adult Immunization Plan 

NAIIS National Adult and Influenza Immunization Summit 
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NAM National Academy of Medicine 

NAP National Action Plan 

NAPNAP National Association of Pediatric Nurse Practitioners 

NAS National Academy of Sciences 

NCEZID National Center for Emerging and Zoonotic Infectious Diseases 

NCHHSTP National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention 

NCHS National Center of Health Statistics 

NCIRD National Center for Immunization and Respiratory Diseases 

NEJM New England Journal of Medicine

NFID National Foundation for Infectious Diseases 

NGO Non-Governmental Organizations

NHANES National Health and Nutrition Examination Survey 

NIAID National Institute of Allergy and Infectious Diseases 

NIC National Immunization Conference 

NICU Neonatal Intensive Care Unit 

NIH National Institutes of Health

NIP National Immunization Program 

NIS National Inpatient Sample 

NIS National Immunization Survey 

NITAG National Immunization Technical Advisory Group 

NMA National Medical Association 

NNDSS National Notifiable Diseases Surveillance System 

NNV Number Needed to Vaccinate 

NOCD New Onset of Chronic Diseases 

NPAIHB Northwest Portland Area Indian Health Board 

NPI Non-Pharmaceutical Intervention

NVSN New Vaccine Surveillance Network 

NVAC National Vaccine Advisory Committee 

NVP National Vaccine Plan

NVPO National Vaccine Program Office 

NVSN New Vaccine Surveillance Network 

NYC New York City

NYC DOHMH New York City Department of Health and Mental Hygiene 

NYS New York State

NYSDOH New York State Department of Health 

OASH Office of the Assistant Secretary for Health 

OID Office of Infectious Disease 

OIDP Office of Infectious Disease Policy and HIV/AIDS 

OPV Oral Polio Vaccine

OSHA Occupational Safety and Health Administration 

PAHO Pan American Health Organization 

PAIVED Pragmatic Assessment of Influenza Vaccine Effectiveness in the DoD 

PALM Pamoja Tulinde Maisha 

PCECV Purified Chick Embryo Cell Vaccine 

PCP Primary Care Practitioner

PCR Polymerase Chain Reaction 

PCV Pneumococcal Conjugate Vaccine

PEP Post-Exposure Prophylaxis

PFU Plaque-Forming Units 
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PHAC Public Health Agency Canada 

PHEIC Public Health Emergency of International Concern 

PhRMA® Pharmaceutical Research and Manufacturers of America®

PI Principal Investigator

PICO Population, Intervention, Comparison, Outcomes 

PIDS Pediatric Infectious Disease Society 

PPE Personal Protective Equipment 

PPV Positive Predictive Value 

PrEP Pre-Exposure Prophylaxis 

PREPARE Pre-Exposure Prophylaxis in Individuals at Potential Occupational Risk for Ebola 

Virus Exposure 

PR Puerto Rico

PREVAC Partnership for Research on Ebola VACcinations 

PREVENT Pregnancy Influenza Vaccine Effectiveness Network 

PRNT Plaque Reduction Neutralization Test 

PT Preferred Terms (MedDRA)

PREVAIL Partnership for Research on Ebola Virus in Liberia 

PUI Persons Under Investigation 

PVRV Purified Vero Rabies Vaccine 

QIV Quadrivalent Influenza Vaccine 

RCT Randomized Controlled Trial

RDT Rapid Diagnostic Test

RFFIT Rapid Fluorescent Focus Inhibition Test

RIG Rabies Immune Globulin 

RIV Recombinant Influenza Vaccine 

RN Registered Nurse

RNA Ribonucleic Acid 

ROA Route of Administration 

RR Relative Risk

rRT-PCR Real-Time Reverse Transcription Polymerase Chain Reaction 

RSV Respiratory Syncytial Virus 

RT-PCR Reverse Transcriptase Polymerase Chain Reaction

rVSV Recombinant Vesicular Stomatitis Virus 

RVV Rabies Virus Variants 

SAB Spontaneous Abortion

SAE Serious Adverse Event 

SAGE Strategic Advisory Group of Experts on Immunization

SAHM Society for Adolescent Health and Medicine 

SARS Severe Acute Respiratory Syndrome 

SCR Seroconversion Rate

SD-IIV3 Standard Dose Inactivated Influenza Vaccine

SEARO South East Asia Regional Office 

SHEA Society for Healthcare Epidemiology of America 

SME Subject Matter Expert

SNS Strategic National Stockpile

STI Sexually Transmitted Infections

STRIVE Sierra Leone Trial to Introduce a Vaccine Against Ebola 

Tdap Tetanus Toxoid, Reduced Diphtheria Toxoid, and Acellular Pertussis

TEC Tribal Epidemiology Center 
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TCH Forecaster Texas Children’s Hospital Immunization Forecasting Software 

TIV Trivalent Influenza Vaccine

tOPV Trivalent Oral Polio Vaccine

UK United Kingdom

UNC University of North Caroline 

US United States

USAMRIID United States Army Medical Research Institute of Infectious Diseases

US Flu VE US Influenza Vaccine Effectiveness Network

USG US Government 

USPHS US Public Health Service 

USU Uniformed Services University 

UTD Up-To-Date 

VA (US Department of) Veteran’s Affairs 

VAERS Vaccine Adverse Event Reporting System

VAPP Vaccine-Associated Paralytic Polio 

VCD Virologically Confirmed Dengue 

VDPV Vaccine-Derived Poliovirus 

VE Vaccine Efficacy

VE Vaccine Effectiveness

VFC Vaccines For Children

VICP Vaccine Injury Compensation Program 

VIS Vaccine Information Statement 

VRBPAC Vaccines and Related Biological Products Advisory Committee Meeting 

VRC Vaccine Research Center (NIAID)

VSD Vaccine Safety Datalink

VSV Vesicular Stomatitis Virus 

WG Work Group

WHO World Health Organization

WPRO Western Pacific Regional Office 

WPV Wild Polio Virus

YF Yellow Fever

ZEBOV Zaïre Ebolavirus 
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

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José Romero, MD, FAAP

ACIP Chair

Amanda Cohn, MD

Executive Secretary, ACIP / CDC

Dr. Romero called to order the February 2020 Advisory Committee on Immunization Practices 

(ACIP) and welcomed those present.

Dr. Cohn welcomed everyone to the February 2020 ACIP meeting. She indicated that the 

proceedings of this meeting would be accessible to people not in attendance via the World Wide 

Web, and welcomed those who could not attend the meeting in person. She pointed out that 

multiple Centers for Disease Prevention and Control (CDC) staff were present at the entrance to

the room and at the desk in the lobby to assist members of the public with questions.

She noted that handouts of the presentations were distributed to the voting ACIP members and 

were made available for members of the public on the tables outside of the auditorium. 

Additionally, slides were made available through a ShareFile link for liaison and ex-officio

members. Slides presented during this meeting will be posted on the ACIP website 

approximately 4 weeks after the meeting. The live webcast videos also will be posted in about 4

weeks following the meeting, and the meeting minutes are posted to the ACIP website generally 

within about 120 days following the meeting. Minutes from the October 2019 meeting were 

scheduled to be posted shortly.

To ensure the health and safety of all individuals attending this meeting, Dr. Cohn reviewed a 

few safety regulations. She explained that in the event of an emergency resulting in an 

evacuation, the procedures would be as follows: 

 Those sitting in the back of the room behind the ropes were instructed to exit out the rear 

doors and across the bridge the way they came in.

 Those sitting in the front of room were instructed to exit through the rear of the room, turn 

left, then proceed right down the stairs.

 Everyone should locate the blue building marker sign labeled “Conference and Meeting 

Space—GCC, 2nd floor” and group together to ensure all attendees are accounted for. 

 Once the premises have been secured and an “all clear” has been issued, participants 

would be permitted to re-enter the building and the meeting would resume. 

The next ACIP meeting will be convened at CDC on Wednesday and Thursday, June 24-25, 

2020. Registration for all meeting attendees is required and will open on the ACIP website when 

the Federal Register notice is published. Registration is not required for webcast viewing.

Call To Order, Welcome, Overview / Announcements, & Introductions 
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Dr. Cohn made the following announcements with regard to liaison organizations, member 

substitutions, and guest attendees for this meeting:

Liaison Organizations 

 The International Society for Travel Medicine (ISTM) joins ACIP as a new liaison member.

The ISTM Liaison Representative is Dr. Elizabeth Barnett, Professor of Pediatrics, Boston

University School of Medicine.

 This will be the last meeting for Dr. David Weber, Liaison Representative for the Society for

Healthcare Epidemiology of America (SHEA). Dr. Weber has served in this role for many

years, and ACIP is very appreciative of his support throughout that time.

 This also will be the last meeting for Dr. Susan Even, the Liaison Representative for the

American College Health Association (ACHA). She too has served in this role for many

years, and ACIP is very grateful for her support throughout that time.

Ex Officio Representatives

 Kara M Elam, PhD, MPH, MS represents the Office of Infectious Disease Policy (OIDP).

 Barbara Mulach, PhD represents the National Institutes of Health (NIH).

Guest Attendees

 During the two days prior to this ACIP meeting, CDC was honored to host the Global

National Immunization Technical Advisory Group (NITAG) Network meeting. ACIP is the

NITAG for the United States (US). Representatives attended from over 50 countries to

discuss how to build NITAGs across the world, and also were in attendance during this

ACIP meeting.

 Students from The Walker School also attend ACIP each year, and were watching the ACIP

meeting from a distance learning center within CDC.

 Students from the University of Alabama School of Public Health attended the second day of

the ACIP meeting.

 In attendance representing the World Health Organization (WHO) Strategic Advisory Group

of Experts on Immunization (SAGE) were Dr. Alejandro Cravioto, current SAGE Chair, and

Dr. John Abrams, former ACIP Chair and former SAGE Chair.

Dr. Cohn emphasized that ACIP is, at its heart, a public body. Engagement with the public and 

transparency in ACIP’s processes is vital to the Committee’s work. As part of ACIP’s 

commitment to continuous improvement, ACIP has strengthened its oral and written public 

comment process to accommodate increased public interest in ACIP’s work, maximize 

opportunities for comment, and make public comment more transparent and efficient. She 

announced that for this meeting, one oral public comment period would be held during the first 

afternoon at approximately 1:15 PM, after lunch, prior to the one anticipated vote of the day on 

Ebola vaccines.

To create a fair and efficient process for requesting to make an oral comment, people interested 

in making an oral comment were asked to submit a request online in advance of the meeting.

Priority is given to these advance requests, and if more people request to speak than can be 

accommodated, a blind lottery is conducted to determine who will be the speakers. Speakers 

selected in the lottery for this meeting were notified in advance of the meeting. Dr. Cohn 

requested that the public comment speakers identified for this meeting sign in at the information 

table outside the main auditorium to confirm their presence. Written public comments may be 

made via regulations.gov using the docket number ID CDC-2020-0002. Information on the 

written public comment process, including information about how to make a public comment, 

can be found on the ACIP website. Regulations.gov closes approximately 24 hours following the 
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

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end of the ACIP meeting. Dr. Cohn pointed out that public comments could be made during and 

after the meeting as well.

As noted in the ACIP Policies and Procedures manual, members of the ACIP agree to forgo 

participation in certain activities related to vaccines during their tenure on the committee. For 

certain other interests that potentially enhance a member’s expertise while serving on the 

committee, CDC has issued limited conflict of interest (COI) waivers. Members who conduct 

vaccine clinical trials or serve on data safety monitoring boards (DSMBs) may present to the 

committee on matters related to these vaccines, but are prohibited from participating in 

committee votes on issues related to those vaccines. Regarding other vaccines of the 

concerned company, a member may participate in discussions with the provision that he/she 

abstains on all votes related to the vaccines of that company. At the beginning of each meeting

and prior to each vote, ACIP members will state any COIs. 

Dr. Cohn indicated that detailed instructions for submission of names of potential candidates to 

serve as ACIP members is now available on the ACIP website. Applications for ACIP 

membership are due no later than July 1, 2020 for the 4-year term beginning July 1, 2021. She 

invited everyone to encourage those they know to submit nominations for ACIP membership, 

and emphasized that they always appreciate both the number of applicants and the 

extraordinary level of expertise in the applicant pool.

Dr. Romero conducted a roll call to determine whether any ACIP members had COIs. No 

members declared any COIs. He then requested that the Liaison and Ex Officio members 

introduce themselves. A list of Members, Ex Officio Members, and Liaison Representatives is 

included in the appendixes at the end of the full minutes from the February 2020 ACIP meeting.

Introduction

Sharon Frey, MD

Chair, Ebola Vaccine Work Group

Saint Louis University Medical School

Dr. Frey reminded everyone that she introduced the new Ebola Vaccine WG during the October 

2019 meeting and that the Ebola Vaccine WG’s terms of reference are to: 1) review the 

available data on the rVSVΔG-ZEBOV-GP vaccine, which is a recombinant vesicular stomatitis 

virus (VSV) with a substituted envelope glycoprotein of the Zaire ebolavirus Kikwit 1995 strain, 

and inform domestic vaccine policy options for ACIP consideration; and 2) inform

recommendations for use of the rVSVΔG-ZEBOV-GP vaccine in pre-exposure vaccination of 

healthy adults ≥ 18 years of age at occupational risk for exposure to Ebola virus (species Zaire 

ebolavirus). There have been several key events since October 2019.

The rVSVΔG-ZEBOV-GP vaccine (ERVEBO®, Merck) was granted EU-wide conditional 

marketing authorization in November 2019. This vaccine is indicated for immunization of 

individuals 18 years of age and older to protect against Ebola virus disease (EVD) caused by 

Ebola virus species Zaire ebolavirus. The US Food and Drug Administration (FDA) approved 

rVSVΔG-ZEBOV-GP vaccine (ERVEBO®, Merck) for individuals 18 years of age or older for the 

Ebola Vaccine
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prevention of EVD on December 19, 2019. On February 12, 2020, the World Health 

Organization (WHO) Emergency Committee unanimously agreed that the ongoing EVD 

outbreak in the Eastern Democratic Republic of Congo (DRC) still constitutes a Public Health 

Emergency of International Concern (PHEIC). 

In terms of the WG’s activities and discussions since October 2019, the WG identified 3 US 

populations at highest risk for potential occupational exposure to Ebola virus for whom potential 

policy options are most urgent, including the following: 

 Individuals responding to an outbreak of EVD due to Ebola virus

 Individuals who work as laboratorians and support staff at Biosafety Level-4 (BSL-4) 

facilities that handle replication competent Ebola virus

 Healthcare personnel (HCP) at federally-designated Ebola Treatment Centers (ETCs) 

involved in the care and transport of confirmed EVD patients

Additional US populations with potential risk for occupational exposure include:

 Healthcare Personnel (HCP) at state or jurisdictionally-designated Ebola Treatment 

Centers

 HCP at Ebola Assessment Hospitals

 HCP at frontline facilities

It is important to note that HPC includes many people of various job descriptions. The formal 

definition utilized by the WG is adapted from the ACIP-approved definitions in the CDC Infection 

Control in Healthcare Personnel guidelines and is as follows:

Healthcare personnel (HCP) refers to all paid and unpaid persons serving in healthcare 

settings who have the potential for direct or indirect exposure to patients or infectious 

materials, including body substances (e.g., blood, tissue, and specific body fluids); 

contaminated medical supplies, devices, and equipment; contaminated environmental 

surfaces; or contaminated air. These HCP include, but are not limited to, emergency 

medical service personnel, nurses, nursing assistants, physicians, technicians, clinical 

laboratory personnel, autopsy personnel, therapists, phlebotomists, pharmacists, 

students and trainees, contractual staff not employed by the healthcare facility, and 

persons not directly involved in patient care, but who could be exposed to infectious 

agents that can be transmitted in the healthcare setting (e.g., clerical, dietary, 

environmental services, laundry, security, engineering and facilities management, 

administrative, billing, and volunteer personnel). 

Since October 2019, the WG has continued discussions on recommendations for additional 

populations at potential occupational risk. They developed a protocol for systematic review of 

vaccine data and selected critical outcomes to be considered. A systematic review was 

conducted of the vaccine literature for a GRADE (Grading of Recommendation Assessment, 

Development and Evaluation) analysis and for evidence to recommend (EtR). The WG has 

engaged in multiple discussions on proposed policy options. 

This session included presentations focused on a review of Ebola virus disease and rVSVΔGZEBOV-GP vaccine, GRADE, EtR, and a summary of WG considerations and proposed policy 

options. 
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Ebola Virus Disease

Mary Choi, MD, MPH

Medical Epidemiologist

Viral Special Pathogens Branch

Centers for Disease Control and Prevention

Dr. Choi reviewed background material to set the stage for the subsequent sessions, including 

background on EVD, rVSVΔG-ZEBOV-GP vaccine, and the parameters for WG discussions 

over the past several months.

In terms of background, EVD in humans is a deadly disease caused by infection with one of 4 

viruses within the genus Ebolavirus and family Filoviridae and are listed here: 

 Ebola virus (species Zaire ebolavirus)

 Sudan virus (species Sudan ebolavirus)

 Tai Forest virus (species Tai Forest ebolavirus)

 Bundibugyo virus (species Bundibugyo ebolavirus)

The remainder of this session focused on the Ebola virus species Zaire ebolavirus. This virus is 

responsible for the majority of reported EVD outbreaks, including the 2 largest outbreaks in 

history. The 2014-2016 West Africa outbreak resulted in a little over 28,000 cases and 11,000 

deaths. The current Eastern DRC outbreak has infected over 31,000 persons and resulted in

over 12,000 deaths in total. Untreated, mortality rates can be as high as 70% to 90%. Currently, 

there is no FDA-approved treatment. 

The animal reservoir for Ebola virus is unknown. However, based on studies in similar viruses, 

the reservoir is believed to be fruit bats. A study was conducted in the early 2000s by Leroy and 

colleagues in which the investigators trapped bats, birds, and rodents in Gabon and the DRC in 

and around areas where there were known Ebola outbreaks in humans and/or animals. They 

were able to identify three species of bats in which Ebola virus was detected by both serology 

and polymerase chain reaction (PCR): Hypsignathus monstrosus, Epomops franqueti, and

Myonycteris torquata. It is important to note that none of these species exist in the US [E M 

Leroy et al., Fruit bats as reservoirs of Ebola virus Nature 438, 575-576 (December 2005)].

The signs and symptoms of EVD include: Abdominal Pain, Bleeding (epistaxis, injection sites), 

Diarrhea, Fatigue, Fever, Headache, Muscle Pain/Joint Pain, Rash, and/or Vomiting. Although 

bleeding can be seen in EVD, it is not universally present and is seen in about 40% of cases. 

When bleeding is observed, it usually is a late sign and pre-terminal. The signs and symptoms 

are non-specific and can be seen in many other diseases that are endemic in Africa. In an 

infected person, Ebola virus can be found in all body fluids, including: Amniotic Fluid, Blood,

Breast Milk, Feces/Vomit, Saliva, Semen, Sweat, Tears, Urine, and Vaginal Secretions. Personto-person transmission occurs through contact with broken or non-intact skin, and/or mucous 

membranes with the body fluids of a person that is sick or has died of EVD.

Those who survive the acute illness often suffer some sequelae. The true incidence of sequelae 

amongst EVD survivors is unknown primarily because these outbreaks occur in countries where 

there is limited access to healthcare or specialized services. Some studies have been 

conducted, particularly following West Africa. The most commonly reported symptoms were 

found to be arthralgia, uveitis, myalgia, abdominal pain, and fatigue1,2. The uveitis can be quite 
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severe and lead to cataract formation and blindness. Following West Africa, a study was 

conducted that found that within one year of discharge, Ebola survivors had 5-fold greater 

mortality than the general population3

. Looking into this further using verbal autopsy, renal 

disease was seen that may have been precipitated by the acute infection. It is also known that 

Ebola virus can persist in immune-privileged sites such as the testes, eyes, brain, and placenta. 

In some, this has resulted in continued disease transmission and disease recrudescence. For 

example, there was a man in Guinea who was 15 months recovered from his illness who then 

transmitted the virus sexually to his partners. This sparked a new cluster of disease that actually 

affected individuals in Guinea and Liberia. The incidence of disease recrudescence that has 

been described in the literature. A British nurse who was infected while working in Sierra Leone, 

fell ill while in the United Kingdom (UK), was treated successfully, and returned to the hospital 

about 9 months after her recovery with meningeal encephalitis, and Ebola virus was detected in 

the nurse’s cerebrospinal fluid (CSF) and eventually the blood as well [1

Rowe et al. Clinical, 

virologic, and immunologic follow-up of convalescent Ebola hemorrhagic fever patients and their 

household contacts, Kikwit, Democratic Republic of Congo; 2

Prevail III Study Group. A 

longitudinal study of Ebola sequelae in Liberia; 3

Keita et al. Subsequent mortality in survivors of 

Ebola virus disease in Guinea: a nationwide retrospective cohort study Lancet Infect Dis. 2019].

On August 1, 2018, an EVD outbreak was declared in Eastern DRC. When the virus responsible 

for the outbreak was sequenced, it was found to be Ebola virus (species Zaire ebolavirus). The 

current outbreak is the 10th outbreak in the DRC and is the largest outbreak to have occurred 

there. In July 2019, the outbreak was declared a PHEIC because of cross-border travel-related 

cases that were detected in Uganda and cases detected in Goma, a very large city in the DRC. 

The PHEIC declaration was reaffirmed in February 2020. As of February 18, 2020, cases had 

been reported in 29 health zones and 3 provinces in the DRC. Case counts were at a little over 

3000 cases and 2000 deaths.

In terms of how the current outbreak compares to other DRC outbreaks in the area from 1976-

2019, the current DRC outbreak has been by far the largest and has lasted the longest. With the 

West Africa outbreak, particularly in Sierra Leone and Liberia, there was a period of time during 

which there was a very rapid increase in the number of cases in which the epidemic curve is 

almost a straight line. The current outbreak in the DRC has not followed that pattern and seems 

somewhat more gradual: 
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There have been 11 individuals treated for EVD due to Ebola virus in the US. All 11 individuals 

were associated with the 2014-2016 EVD outbreak in West Africa. Of these, 9 were infected in 

West Africa and 2 (18%) died. There was one imported case of EVD that resulted in secondary 

transmission in 2014 in Dallas, Texas. In addition to these 11 EVD patients, additional 

individuals have been repatriated to the US following high-risk exposures to Ebola virus, but 

none of these individuals tested positive. This repatriation occurred during the 2014-2016 West 

Africa outbreak and the current DRC outbreak.

There is a live-attenuated vaccine recombinant (rVSV)-based Ebola virus vaccine (rVSVΔGZEBOV-GP). It is important to note that the vaccine cannot cause Ebola virus infection. This 

vaccine initially was developed by Public Health Agency Canada (PHAC) and NewLink 

Genetics. Merck currently holds the intellectual rights. The vaccine protects only against Ebola 

virus (species Zaire ebolavirus). In December 2019, the FDA licensed the vaccine for individuals 

18 years of age or older for the prevention of EVD.

In terms of the vaccine construct, the glycoprotein (GP) was removed from the VSV and was 

replaced with the GP of the Zaïre ebolavirus (Kikwit). The vaccine contains this recombinant 

virus. Once a person receives the vaccine, the virus will replicate and the person with develop 

antibodies toward the GP. The vaccine is administered as a one-time 1.0 mL dose by the 

intramuscular (IM) route. There are specific storage requirements for this vaccine. It must be 

stored between -80o

C and -60oC. Once thawed, it can be stored at 2oC to 8oC for up to 2 weeks.

Animal studies were conducted on this vaccine to assess effectiveness in preventing Ebola 

virus. Cynomolgus macaques were vaccinated with various doses of the vaccine and then 

challenged with live virus 42 days later and examined survival. At 2x107 and up, protection 

100%. At 3x106

, protection was 88%. Following the animal studies, multiple clinical studies were 

conducted throughout the world in the US, Canada, Africa, and Europe.

In regard to safety, there is generally a mild to moderate transient reactogenicity is commonly

reported within 24-48 hours of vaccination that typically resolves within 7 days. Some of the 

common signs and symptoms during this period include injection site pain, swelling, erythema, 

fever/subjective fever, muscle aches, malaise, and headache. Arthralgia and arthritis reported in 

some vaccinees. Vaccine-related serious adverse events (SAEs) are rare. 
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The rVSV has been detected in bodily fluids. Virus dissemination and replication can occur and 

persist for up to 2-3 weeks after vaccination. It has been detected in blood, which is expected 

because it is a live virus that replicates. It has been detected by PCR in blood as long as 14 

days after vaccination. It also has been detected in urine for up to 7 days, saliva up to 14 days, 

synovial fluid up to 17 days, and skin vesicles up to 17 days post-vaccination.

With regard to immunogenicity, there is no known immune correlate for protection. A measure of 

the immune response that confers protection against EVD is unknown. It is thought that the 

protective effect of the vaccine conferred by vaccination is a combination of both innate and 

adaptive immune response activation. As measured by enzyme-linked immunosorbent assay 

(ELISA), the GP-specific IgG antibodies begin to rise at around Day 14 and can persist through 

24 months post-vaccination. 

This vaccine has been used in the outbreak setting in the Ça Suffit trial. The results of this trial 

were reported in 2 parts. It was a Phase 3, cluster-randomized, open-label ring vaccination trial. 

The trial took place in Guinea at a time when the 2014-2016 West Africa EVD outbreak was 

waning. A ring vaccination strategy was used to administer the vaccine, in part to generate 

robust data on vaccine efficacy (VE) in the setting of a waning outbreak. In this study, a cluster 

was defined around a confirmed case of EVD. The primary outcome was incidence of EVD with 

onset 10 days or more after randomization. This 10-day period was to account for the incubation 

period of EVD and the unknown time for the vaccine to develop protective immunity. 

In terms of the interim results, clusters were randomized to immediate vaccination or delayed 

vaccination at 21 days after randomization. In this study, VE was found to be 100% (95%CI: 

74.7-100, p=0.0036). Basically, the investigators identified the index case (confirmed case) and 

then defined contacts and contacts of contacts. This became the clusters, which were then 

randomized to immediate or delayed vaccination. In July 2015, randomization was discontinued 

at the recommendation of the Data and Safety Monitoring Board due to the interim findings of 

100% VE. All subsequent clusters were offered immediate vaccination. The final results were 

reported on VE for randomized and non-randomized clusters, and again VE was reported to be 

100% (95%CI: 68.9-100, p=0.0045) [Courtesy of Merck].

In the DRC, ring vaccination was started 1 week after the outbreak was declared and has 

evolved over time. The vaccine has now been administered to over 200,000 people using this 

strategy. The vaccine appears to be effective and SAEs have been rare. This graphic depicts 

the ring vaccination strategy being used in DRC: 

Courtesy of Dr. Henao-Restrepo
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In terms of the parameters of the WG discussions over the last several months, consideration 

was given to the fact that the suspected virus reservoir does not exist in the US, most of the 

inviduals (9/11) treated for EVD in the US were responding to a foreign EVD outbreak, there is 

an ongoing EVD outbreak in Eastern DRC that is considered a PHEIC, and there is no EVD 

outbreak in the US. As such, the WG’s deliberations focused on pre-exposure vaccination in US 

populations at immediate occupational risk.

As mentioned earlier, 3 US populations were identified as being at highest risk for potential 

occupational exposure to Ebola virus (species Zaire ebolavirus) for whom potential policy 

options are most urgent: 1) individuals responding to an outbreak of EVD due to Ebola virus; 2) 

individuals who work as laboratorians and support staff at Biosafety Level-4 (BSL-4) facilities 

that handle replication competent Ebola virus; and 3) HCP at a federally-designated ETCs

involved in the care and transport of confirmed EVD patients. Additional US populations with 

potential risk for occupational exposure include: 1) HCP at state or jurisdictionally-designated 

ETCs; 2 ) HCP at Ebola Assessment Hospitals; and 3) HCP at frontline facilities. Discussions 

and recommendations of these groups are still ongoing.

Looking at the 3 additional populations more in-depth, the number of individual organizations 

responding to an outbreak will vary by size and location of the outbreak. There were over 4000 

US government (USG) deployers to the 2014-2016 West Africa EVD outbreak, including the 

domestic EVD cases. US responders to the current eastern DRC outbreak include over 200 

non-governmental organization (NGO) personnel and over 300 governmental personnel form 

CDC, NIH, and the United States Agency for International Development (USAID). 

There are 10 BSL-4 laboratories in the US, with an estimated 350 to 400 laboratory and support 

staff, of which 8 currently handle replication-component Ebola virus. There are 11 federallydesignated Ebola Treatment Centers in the US that are specialized high-level isolation units 

equipped with infrastructure, laboratory capabilities, staff to care for patients with highly 

hazardous communicable diseases. These include the regional Special Pathogen Centers and 

NIH. These facilities are estimated to have approximately 500 HCP and support staff.

Discussion Points

Dr. Bernstein wondered about the clinical significance of the live attenuated vaccine not being 

able to cause disease, but being detected in certain bodily fluids up to 2 to 3 weeks.

Dr. Choi responded that the viremia is expected and most people clear it within a week or so. 

One study did find it as far as 14 days post-vaccination. It has been detected as shedding in 

saliva and urine, but no attempts were made to isolate it. When something is detected by PCR, 

it just means that it was possible to detect the nucleic acids and does not necessarily mean live 

virus. Some individuals developed a vesicular rash after vaccination, from which virus was 

isolated. There certainly is a concern about what that translates to in terms of transmission 

potential, particularly with rash that is shedding. This was one of the outcomes of interest in the 

GRADE analysis. After people are vaccinated in the Pre-Exposure Prophylaxis in Individuals at 

Potential Occupational Risk for Ebola Virus Exposure (PREPARE) clinical trial that is offering 

vaccination, precautions are given in terms of contact and what to do if a vesicular rash 

develops.

Dr. Hunter requested confirmation that Dr. Choi was talking about transmission of viral 

stomatitis, not of Ebola. He wondered what the worst clinical sequalae would be assuming that 

the viral strain would cause viral stomatitis if it were to transmit.
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Dr. Choi clarified that it would be recombinant vaccine virus, not Ebola. VSV is found primarily in 

livestock. In situations where there have been outbreaks of VSV in livestock, there has been 

transmission into humans who handle livestock. There also has been transmission to humans 

because this virus backbone is a very popular one for other vaccines as well. There have been 

transmissions to laboratory personnel by accidental exposures. In humans, infection with VSV 

can be asymptomatic. If it becomes symptomatic, oftentimes it results in an influenza-like 

illness. The vesicular type of rash and oral ulcer has been observed in humans. Typically, 

arthritis and arthralgia have been seen with this virus but has not been seen in humans with 

VSV. In animals, it causes vesicular lesions in the oral mucosa and utters. Arthritis or arthralgia 

have not been seen in that population.

Regarding the definition of HCP and not specific to Ebola, Dr. Lee noticed that physician 

assistants (PA) and nurse practitioners (NP) were not included in the updated definition. She 

also noted that based on Slide 27 of Dr. Choi’s presentation, it appeared that the ring 

vaccination strategy was now evolving in the DRC. She wondered if one way to think about the 

categories of people who might be at highest risk in terms of pre-exposure prophylaxis (PrEP) 

as that ring strategy continues to evolve would be more generalized to Ring 1 as the focus 

because additional subgroups might be identified who could benefit from vaccination.

Dr. Choi said she thought they probably try to make a distinction between what CDC is trying to 

make recommendations for and what is occurring in the DRC. CDC is trying to make 

recommendations for PrEP for people who have not been exposed in an attempt to protect them 

from a future exposure. In the DRC, this is different. Some pre-exposure vaccination is being 

done among HCP and frontline workers. For the most part, ring vaccination is done postexposure. The ring is defined around a confirmed case where an outbreak occurring. Given that 

there is no outbreak or reservoir in the US, if there is an infection of EVD it is known to have 

come from either a foreign outbreak that was imported to the US or a BSL-4 laboratorian who 

was exposed while working with Ebola. They talk about the Ça Suffit trial and included it in the 

GRADE analysis because it showed efficacy, but many other clinical studies were conducted on 

this vaccine that attempted to show efficacy. By the time the studies were done, the outbreak 

was over and there were no other cases. While the Ça Suffit trial showed efficacy, it was in the 

setting of an outbreak and a post-exposure type of picture.

Dr. Lee clarified that she understood the difference between the pre- and post-exposure, but 

thought the group ACIP was interested in would be those with high-risk contacts with patients or 

their body fluids. She just wanted to harmonize the way they were thinking about the three 

groups to ensure that they are not exclusive of other people who potentially might be exposed.

Dr. Frey expressed appreciation for Dr. Lee’s comments and emphasized that the WG would be 

assessing the groups in more detail moving forward. There is a PREPARE trial in which those 

working on the frontlines or are going to be deployed out can participate. 

Thinking about the untreated mortality rate of 70% to 90% and the deaths of 2 of 11 subjects in 

the US, Dr. Bernstein inquired as to whether efforts for support have made a difference in 

Africa.

Dr. Choi indicated that mortality is 79% with no supportive treatment in Africa. With early 

supportive treatment alone, mortality is reduced to as low as 40%. In the current outbreak, the 

Pamoja Tulinde Maisha (PALM) trial was conducted in which experimental therapies were 

tested. These included ZMapp and remdesivir used in West Africa and 2 new monoclonal 
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antibodies, MAb114 and REGN-EB3. In this randomized clinical control trial (RCT), the control 

was ZMapp. This study found that there was a reduction in mortality in particular with the 2 

monoclonal antibodies. The therapeutics are continuing to be given in-country, but this is limited 

to the 2 monoclonal antibodies.

GRADE: rVSVΔG-ZEBOV-GP Ebola Vaccine

Caitlin Cossaboom, DVM, PhD, MPH

LT US Public Health Service

Viral Special Pathogens Branch

Division of High-Consequence Pathogens and Pathology

Dr. Cossaboom presented the GRADE analysis of the newly licensed Ebola vaccine, which she 

referred to as rVSV moving forward in the presentation. The policy question for consideration is, 

“Should pre-exposure vaccination with the rVSV Ebola vaccine be recommended for healthy, 

non-pregnant, non-lactating adults 18 years of age or older in the US population who are at 

potential occupational risk to exposure to Ebola virus (species Zaire ebolavirus) for prevention 

of Ebola virus infection?” 

She then reviewed the population, intervention, comparison, and outcomes of interest (PICO) 

determined by the ACIP Ebola Vaccine WG. The population of interest is healthy, non-pregnant, 

non-lactating adults 18 years of age or older in the US population who are at risk of 

occupational exposure to Ebola virus within the following three subgroups: 1) Individuals 

responding to an outbreak of EVD due to Ebola virus; 2) healthcare personnel involved in the 

care and transport of confirmed EVD patients at federally-designated ETCs in the US; and 3) 

laboratorians and support staff working in BSL-4 laboratories that handle Ebola virus. The 

intervention of interest is pre-exposure intramuscular immunization with a single licensed dose 

of the rVSV Ebola vaccine, while the comparison was no vaccine. The outcomes the WG

considered critical and that were subjected to analysis were: development of Ebola-related 

symptomatic illness; Ebola-related mortality which was not analyzed as there was no available 

data for this outcome; vaccine-related joint pain or swelling; vaccine-related adverse pregnancy 

outcomes for women inadvertently vaccinated while pregnant and women who become 

pregnant within 2 months of vaccination; transmissibility of rVSV vaccine virus surrogate 

assessed with viral dissemination/shedding of the rVSV vaccine virus; and SAEs related to 

vaccination. There were two additional outcomes that the WG considered important, but not 

critical, that included the incidence and severity of oral or skin lesions and the interaction or 

cross-reactivity with monoclonal antibody-based therapeutics or other VSV-backboned 

vaccines. However, data for these outcomes have not been analyzed to-date and were not

included in this presentation.

Of the critical outcome measures that were included in the evidence profile for this presentation, 

the following five outcomes were included for meta-analyses: the benefit outcome of 

development of Ebola-related symptomatic illness; and the safety outcomes of incidence and 

severity of arthralgia, incidence of arthritis, and vaccine-related adverse pregnancy outcomes 

for women inadvertently vaccinated while pregnant and women who become pregnant within 2 

months of vaccination. The four remaining outcomes were included for descriptive analyses 

only: detection of rVSV vaccine virus in blood or plasma (viremia); detection of rVSV vaccine 

virus in saliva (viral shedding); detection of rVSV vaccine virus in urine (viral shedding); and 

SAEs related to vaccination. 
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On December 16, 2019, a literature search was executed in multiple biomedical and 

interdisciplinary bibliographic databases using a broad and rigorous search strategy that 

incorporated terms related to vaccination against Ebola virus using the rVSV Ebola vaccine, 

without date or language restrictions. Results were compiled in an EndNote library and duplicate 

records were removed. This search was updated on January 31, 2020 to screen recent records 

that were not captured in the original search. An attempt also was made to obtain unpublished 

or other relevant data not included in the search results from subject matter experts (SMEs) and 

the manufacturer and received one additional record for inclusion in the analysis. 

Records were included for analysis if they presented data on the rVSV Ebola vaccine and 

involved immunocompetent adults 18 years of age or older regardless of pregnancy status, 

included data for the intervention of interest and data relevant to the outcome measures being 

assessed, and reported primary data from comparative or single-arm studies, RCTs, 

prospective or retrospective cohort, case-control, or cross-sectional studies. In total, 1818 

records were identified through the database searches and the one unpublished record

mentioned was identified through other sources. A total of 1742 of these records were excluded 

during title and abstract screening, leaving 77 full-text articles that were assessed for eligibility 

through full-text review. Of these, 59 full-text articles were excluded for these reasons: 41 were 

not relevant to the outcomes, 8 used the wrong study design, 7 were abstracts later published in 

full, 2 included the wrong intervention, and 1 had the wrong population. In total, 18 articles that 

presented data from 11 studies were included in qualitative synthesis while 9 articles that 

presented data from 8 studies were included in quantitative synthesis or meta-analysis. The 

references for the articles utilized in the analyses are shown here, with those included in the

meta-analyses shown in black and those included in the descriptive analyses only shown in 

blue:
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The GRADE approach for assessing the type or quality of evidence involves consideration of 

several criteria. Assessing the type or certainty level of the body of evidence for each outcome 

begins with the study design. RCTs are initially classified as Evidence Type 1 or high certainty 

and observational studies as Evidence Type 3 or low certainty. Following the identification of the 

initial evidence type, the body of evidence for each outcome is assessed and downgraded if 

there is uncertainty about any of the five following criteria: risk of bias, inconsistency which 

considers statistical heterogeneity and I2 or the variation across studies due to heterogeneity 

greater than chance, indirectness or the generalizability of the body of evidence to the original 

PICO components, imprecision which considers the fragility of the relative and absolute effect 

measures as they relate to the 95% confidence intervals and optimal information size, and 

publication bias. The body of evidence from observational studies may be rated up due to doseresponse gradient, large or very large magnitude of effect, or opposing residual confounding, 

considered under “other considerations.” After assessing on the described criteria, the body of 

evidence will be assigned an overall evidence type or certainty level as defined in the following 

table:

Type 1 (high certainty): We are very confident that the true effect lies close to that of the 

estimate of the effect.

Type 2 (moderate certainty): We are moderately confident in the effect estimate: The true effect 

is likely to be close to the estimate of the effect, but there is a 

possibility that it is substantially different.

Type 3 (low certainty): Our confidence in the effect estimate is limited: The true effect 

may be substantially different from the estimate of the effect. 

Type 4 (very low certainty): We have very little confidence in the effect estimate: The true 

effect is likely to be substantially different from the estimate of 

effect.

As a reminder, these are not a measure of how well the individual studies were conducted, but 

rather how much confidence there is in the estimates of effect from the body of evidence across 

each outcome. For the purposes of the evidence assessment, RCT refers to a trial which 

randomizes participants to an active intervention or a placebo or unvaccinated comparator arm. 

Observational studies refer to one-arm studies, studies for whom participants were not 

randomized, or studies that did not provide disaggregated data to allow for the comparison 

between the randomized arms. Evidence also was considered observational if only data from 

the vaccinated study arms were included in analysis for a given outcome. 

For Outcome 1 (development of Ebola-related symptomatic illness), there was one published 

study with an unvaccinated comparator that was included for the body of evidence for this 

outcome by Henao-Restrepo 2017. This is publication associated with the Ça Suffit Trial in 

Guinea. This was a 2-part Phase 3 cluster-randomized open-label ring vaccination trial. The 

initial study involved contacts and contacts of contacts of confirmed Ebola virus disease or EVD 

cases that were randomized to either immediate or delayed vaccination. Delayed vaccination 

was defined as vaccination that occurred 21 days after randomization. A follow-up study 

included immediate vaccination following cessation of the randomized trial. The primary 

outcome was the incidence of EVD with onset of 10 days or more following randomization. The 

10 days accounts for the average incubation period of Ebola and unknown time for the vaccine 

to induce protective immunity.
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Walking through the table that presents the body of evidence for the outcome of development of 

Ebola related symptomatic illness from the one published study Henao-Restrepo 2017, Dr. 

Cossaboom focused on the development of EVD 10 days or longer after randomization (or for 

non-randomized participants, 10 days or longer after inclusion in the ring) because as explained

earlier, these 10 days account for the incubation period and unknown duration to immunity. Out 

of 3775 participants within 70 clusters who received immediate vaccination between 

randomized and non-randomized, 0 participants developed EVD 10 days or longer after 

randomization. In contrast, of 4507 participants within 104 clusters who were delayed or never 

received the vaccine, 23 participants within 11 clusters developed EVD 10 days or longer after 

randomization. Focusing on only the participants within the randomized clusters, out of 2108 

participants within 51 clusters who received immediate vaccination, 0 developed EVD greater 

than 10 days after randomization. In contrast, of 3075 participants within 47 clusters who were 

randomized to delayed vaccination, 16 participants within 7 clusters developed EVD greater 

than 10 days after randomization. These randomized data equate to a calculated vaccine 

efficacy of 100% (95% confidence interval 68.9 – 100).

Given that this was a cluster RCT in which the units of randomization were clusters, Dr. 

Cossaboom presented randomized cluster-level data. Using the randomized cluster level data 

presented on the previous slide (Slide 17) it equates to a risk ratio of 0.06. Because the 

population in this study consists of contacts and contacts of contacts of EVD cases and used a 

ring vaccination strategy that may include post-exposure vaccination, this was downgraded one 

level for indirectness to the US population and the intervention of interest, which is pre-exposure 

vaccination. For this cluster-level data, there were few events reported and the data do not meet 

the optimal information size and suggest fragility of the estimate, and the confidence interval 

crosses 1 and contains the potential for desirable as well as undesirable effects, so it was 

downgraded one level for imprecision. To provide some context, there were few events of 

confirmed Ebola reported even among the unvaccinated arm because this study was conducted 

at a time when the 2014-2015 West Africa outbreak was waning in Guinea. Taking into account 

this assessment, the overall assessment of this body of evidence at the randomized cluster 

level to address the outcome of development of Ebola-related symptomatic illness is Type 3 or 

low certainty evidence.

From the same study, Dr. Cossaboom presented participant level data from the randomized 

clusters that support there is a benefit of vaccination among those who are vaccinated, which 

was considered observational because the units of randomization within the study were 

clusters. Because a very precise decrease was seen in the non-randomized group, this was not 

rated down for imprecision at the participant level. This was rated down one level for 

indirectness for the same reason as the cluster-level data; however, the concerns with 

indirectness do not pose an inflationary effect and, therefore, the evidence could be rated up 

based on the very large magnitude of effect from the 96% relative risk reduction. Taken 

together, overall certainty was upgraded two levels to Type 2 or moderate certainty evidence for 

this participant level data. 

Outcome 2 (incidence of arthralgia) was assessed with the incidence of arthralgia or joint pain 

that was solicited within 0-42 days, with the results of a meta-analysis of 6 studies that solicited 

arthralgia within 0-42 days presented in a forest plot. It is important to note that across these 

studies, variable definitions for arthralgia were used, including joint pain with or without joint 

swelling or effusion, and in some cases a definition was not provided. Additionally, length and 

time of follow-up varied between studies. An analysis was conducted that stratified by duration 

of follow-up and it did not have an impact on effect estimates for this analysis; however, there is 

a concern that pooling these data may under-estimate incidence because of this variability in 
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

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follow-up time. Additionally, the data presented are varying across doses or plaque forming 

units (PFUs) of vaccine. However, after conducting a separate analysis that stratified by dose, 

there does not seem to be a dose-response or effect on this outcome. Taken together, the 

calculated risk ratio from these 6 RCTs was 2.55. There were also two non-randomized studies 

with non-vaccinated comparators that were analyzed separately with a calculated risk ratio of 

1.63. Additionally, across 7 studies that did not have a comparison group, 1546 out of 8329 

(16%) of vaccinated participants reported arthralgia. 

Looking at the body of evidence for the 6 randomized trials, overall, among 1874 vaccinated 

participants, 316 (16.9%) reported arthralgia compared with 42 out of 891 (4.7%) of nonvaccinated participants. This equates to a relative risk of 2.55 and an absolute risk of 73 more 

events of arthralgia out of 1000 people. This body of evidence was downgraded one level for a 

concern for risk of bias because of lack of blinding in participants, healthcare personnel, and 

outcome assessors in two studies that may have influenced events reported for this outcome. 

Additionally, there is a concern for underreporting in one study that only solicited arthralgia at 

one week and one month for the majority of participants, that may have led to underreporting of 

events. Due to concerns with heterogeneity with an I squared of 70%, this was downgraded one 

level for inconsistency. Because the 95% confidence interval crosses 1 and includes a potential 

for possible harms as well as benefits, a downgrade was made one level for imprecision.

Overall, this body of evidence was assessed to be Type 4 very low certainty evidence. 

Looking at the body of evidence for the two observational studies, overall, among 469 

vaccinated participants, 75 (16.0%) reported arthralgia compared with 8 out of 99 (8.1%) of nonvaccinated participants. This equates to a relative risk of 1.63 and an absolute risk of 51 more 

events of arthralgia out of 1000 people. Because there were few events reported suggesting 

fragility in the estimate, this was downgraded one level for imprecision. Overall, this body of 

evidence was assessed to be Type 4 or very low certainty evidence.

Outcome 3 (severity of arthralgia) was assessed with the incidence of severe (Grade 3) 

arthralgia solicited between 0-42 days and defined as significant joint pain or discomfort that 

prevents daily activity. For background, arthralgia is described on a Grade 1 to 4 scale:

 Grade 1: Mild; No interference with activity

 Grade 2: Moderate; Some interference with activity

 Grade 3: Significant; prevents daily activity

 Grade 4: Potentially life-threatening Medical consultation and/or hospitalization 

In terms of the results of a meta-analysis of 4 studies with that reported on incidence of severe 

arthralgia within 0-42 days, it is important to note that similar to the previous outcome, across 

these studies, variable definitions for arthralgia were used. Additionally, time of follow-up and 

dose or PFU of vaccine used varied between studies. However, similar to the previous outcome, 

these did not have an impact on effect estimates. Taken together, the calculated risk ratio from 

these 4 RCTs was 6.4. There also were two non-randomized studies with non-vaccinated 

comparators that were analyzed separately and reported no events of Grade 3 arthralgia among 

469 vaccinated and 99 non-vaccinated participants. Additionally, across 5 studies that did not 

have a comparison group, 7 out of 7209 (0.1%) of vaccinated participants reported Grade 3 

arthralgia. There were no reports of Grade 4 arthralgia across the body of evidence.
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

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Walking through the evidence table for assessment of the body of evidence for Outcome 3, 

looking at the body of evidence for the four randomized trials, overall, among 333 vaccinated 

participants, 2 (0.6%) reported severe arthralgia compared with 0 out of 264 non-vaccinated 

participants. This equates to a relative risk of 6.4 and an absolute risk of 0 more events of 

severe arthralgia out of 1000 people. This body of evidence was downgraded one level for a 

concern for risk of bias because of lack of blinding in participants, healthcare personnel, and 

outcome assessors in two studies that may have influenced events reported for this outcome. 

Because of a concern for fragility in the estimate due to the few number of events reported, this 

was downgraded one level for imprecision. Overall, this body of evidence was assessed to be 

Type 3 low certainty evidence. Looking at the body of evidence for the 2 observational studies, 

overall, no events of Grade 3 arthralgia were reported among 469 vaccinated and 99 nonvaccinated participants. Because there were no events reported among vaccinated and nonvaccinated participants, it suggests fragility in the estimate, this was downgraded one level for 

imprecision. Overall, this body of evidence was assessed to be Type 4 very low certainty 

evidence.

Outcome 4 (incidence of arthritis) was assessed with an event of arthritis reported within 5-56 

days of follow-up. Based on the forest plot presenting the results of a meta-analysis of 4 studies 

that solicited arthritis within 5-56 days, it is important to note that each of these studies defined 

and diagnosed arthritis with considerable variability as follows:

 Kennedy 2017: Concern for underreporting because low % of female enrolled 

participants (37%); Kennedy only solicited at week 1 and at month 1

 Samai 2018: No capability of clinical diagnosis of arthritis, no rheumatology services 

available in Sierra Leone

 El Sherif 2017: Did not provide definition for arthritis

 Huttner 2015: first to encounter arthritis, so thoroughly clinically investigated arthritis (all 

participants with arthritis referred to rheumatologist, all but 2 participants with arthritis 

had an u/s done); this study is not included in the RCT analysis because arthritis was 

reported only in low dose participants and upon request de-aggregated data was 

unavailable

Additionally, time of follow-up and dose or PFU of vaccine used varied between studies. 

However, similar to the previous outcome, these did not have an impact on effect estimates. 

Taken together, the calculated risk ratio from these 4 RCTs was 1.8. There also were 2 nonrandomized studies with non-vaccinated comparators that were analyzed separately and had a 

comparable effect size and lower precision. Additionally, across 2 studies that did not have a 

comparison group, 2 out of 50 (4%) of vaccinated participants reported arthritis. Additionally, 

three published studies reported on the detection of vaccine virus in synovial fluid. This data 

was not included in the evidence tables; however, the WG felt that it was directly applicable to 

this outcome and supports causality between vaccination and arthritis, so it was presented 

descriptively. Across this body of evidence, vaccine-virus has been detected by reverse 

transcriptase polymerase chain reaction (RT-PCR) in 4 out of 7 vaccinated participants who

have had synovial fluid tested. Viral isolation was attempted on one synovial fluid specimen and 

was negative.
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Looking at the body of evidence for the four randomized trials for Outcome 4, overall, among 

1776 vaccinated participants, 39 (2.2%) reported severe arthralgia compared with 16 out of 868 

(2.1%) non-vaccinated participants. This equates to a relative risk of 1.8 and an absolute risk of 

23 more events of arthritis out of 1000 people. This body of evidence was downgraded one level 

for a concern for risk of bias because the studies used variable definitions and methods for 

diagnosing and reporting arthritis, and for lack of blinding in participants, healthcare personnel, 

and outcome assessors in two studies that may have influenced events reported for this 

outcome. Because the 95% confidence interval crosses 1 and includes a potential for possible 

harms as well as benefits, the evidence was downgraded one level for imprecision. Overall, this 

body of evidence was assessed to be Type 3 low certainty evidence. Looking at the body of 

evidence for the two observational studies, overall, 43 out of 520 vaccinated recipients reported 

arthritis compared to 3 out of 107 unvaccinated participants. This equates to a risk ratio of 2.06 

and an absolute risk of 33 more events of arthritis out of 1000 people. Because of concern for 

fragility in the estimate due to the few number of events reported and that the 95% confidence 

interval crosses 1 and includes a potential for possible harms as well as benefits, the evidence 

was downgraded two levels for imprecision. Overall, this body of evidence was assessed to be 

Type 4 very low certainty evidence.

For Outcome 5 (vaccine-related adverse pregnancy outcomes for women inadvertently 

vaccinated while pregnant and women who become pregnant within 2 months of vaccination

that was assessed with incidence of pregnancy loss defined as spontaneous abortion and 

stillbirth), there was one study included in the body of evidence, Legardy-Williams 2020, which 

was a non-randomized sub-study of the Sierra Leone Trial to Introduce a Vaccine Against Ebola

(STRIVE). In this study, 14 out of 31 (45%) pregnant women who received immediate 

vaccination experienced pregnancy loss compared to 11 out of 33 (33%) of unvaccinated 

pregnant women. Overall, the rate of pregnancy loss between these groups was not significantly 

different. Among live births, no external congenital anomalies were detected among either 

group. Further studies with larger sample sizes would be needed to rule out a meaningful 

difference in the percentage of pregnancy loss, pregnancy complications, or birth defects. There 

were 3 additional studies that reported on this outcome that did not have comparison groups. 

Among these 3 studies, there were 3 adverse pregnancy outcomes out of 20 pregnancies in 19 

women; however, no conclusions can be made regarding the relationship between vaccination 

and adverse pregnancy outcomes based on these data. 

In terms of the body of evidence for Outcome 5, in the one observational study with a 

comparator, 14 out of 31 (45%) pregnant women who received immediate vaccination 

experienced pregnancy loss compared to 11 out of 33 (33%) of unvaccinated pregnant women. 

This equates to a relative risk of 1.35 and an absolute risk of 117 more events of pregnancy loss 

out of 1000 people. This evidence was downgraded one level for indirectness because the 

study did not differentiate between spontaneous abortions, including induced abortion, and 

stillbirth and the outcome may not accurately distinguish between events due to the vaccine. 

Additionally, because of there being a concern for fragility in the estimate due to the few number 

of events reported and that the 95% confidence interval crosses 1 and includes a potential for 

possible harms as well as benefits, the evidence was downgraded two levels for imprecision. 

Overall, this body of evidence was assessed to be Type 4 very low certainty evidence.
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

29

For Outcome 6a (the transmissibility of vaccine virus, with a surrogate of vaccine virus 

dissemination assessed with detection of rVSV in blood/plasma by RT-PCR), data from 8 

studies were included for the body of evidence for this outcome. Across these 8 studies, on day 

7 post-vaccination, 32 out of 691 (4.6%) vaccinated participants were RT-PCR positive for 

vaccine virus. On day 14 post-vaccination, 1 out of 501 (0.2%) of vaccinated participants were 

RT-PCR positive for vaccine virus. Additionally, one study performed viral isolation on selected 

blood specimens and all were negative.

To summarize the body of evidence for the surrogate outcome of detection of rVSV in 

blood/plasma by RT-PCR, the longest recorded positive is 14 days post-vaccination. While 

these 8 studies include both RCT and non-randomized studies, for the purposes of this 

outcome, only data from the vaccinated arms were included for analysis. As discussed 

previously, the studies were considered observational for this outcome. This evidence was 

downgraded one level for risk of bias because of concern for incomplete outcome data as not all 

who received the vaccine were tested on a given day. It also was downgraded 2 levels for 

indirectness because the outcome of interest to the WG was transmissibility of the vaccine virus 

to humans or animals. There are no data that report on transmissibility, so viral dissemination 

and shedding is assessed as an indirect surrogate. Additionally, RT-PCR positivity is not 

synonymous with infectivity. Overall, this body of evidence was assessed to be Type 4 or very 

low certainty evidence.

For Outcome 6b (transmissibility of vaccine virus, with a surrogate of vaccine virus 

dissemination assessed with detection of rVSV in saliva and urine by RT-PCR), data were 

included from 4 studies for the body of evidence for this outcome. Across these 4 studies, on 

day 7 post-vaccination, 6 out of 257(2.3%) vaccinated participants were RT-PCR positive for 

vaccine virus in saliva while 2 out of 246 (0.8%) were positive in urine. On day 14 postvaccination, 1 out of 98 (1%) of vaccinated participants were positive in saliva while 0 out of 98 

were positive in urine.

To summarize the body of evidence for the surrogate outcome of detection of rVSV in saliva 

and urine by RT-PCR, the longest recorded positive in saliva is 14 days post-vaccination and 

the longest recorded positive in urine is 7 days post-vaccination. Like the previous outcome, 

only data from the vaccinated arms were included for analysis, so the studies were considered 

observational for this outcome. This evidence was downgraded one level for risk of bias 

because of concern for incomplete outcome data as not all who received the vaccine were 

tested on a given day. The evidence also was downgraded 2 levels for indirectness because 

like the previous outcome, no data report on transmissibility, so viral dissemination and 

shedding is assessed as an indirect surrogate and RT-PCR positivity is not synonymous with 

infectivity. Overall, this body of evidence was assessed to be Type 4 very low certainty 

evidence.

Across the body of evidence for Outcome 7 (vaccine-related SAEs), 12 studies with unique 

populations reported on vaccine-related SAEs. Out of 19,184 people who received the vaccine 

across these 12 studies, 3 SAEs judged to be related or possibly related to the vaccine were 

reported. Two of these were related to vaccination and included a febrile reaction and 

anaphylaxis, both of which resolved without sequelae. One was judged to be possibly related to 

the vaccine, an influenza like illness, which also resolved without sequelae. In summary, the 

majority of studies did not report any vaccine related SAEs. 
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

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To summarize the body of evidence for outcome of vaccine-related SAEs, vaccine-related AEs 

are an uncommon occurrence. Across 12 studies, 3 of 19,184 (0.02%) vaccinees were judged 

to have an SAE related to or possibly related to vaccination. Like the previous outcome, only 

data from the vaccinated arms were included for analysis, so the studies were considered 

observational for this outcome and were not downgraded across any of the criteria. Overall, this 

body of evidence was assessed to be Type 3 low certainty evidence.

Evidence to Recommendations for Pre-Exposure Vaccination With 

rVSVΔG-ZEBOV-GP Vaccine for At-Risk Adults in the United States

Mary Choi, MD, MPH

Viral Special Pathogens Branch

Centers for Disease Control and Prevention

Dr. Choi reminded everyone of the policy question and PICO. The first EtR question is, “Is the 

problem of EVD due to Ebola virus (species Zaire ebolavirus) of public health importance?” For 

this question, the WG considered that Ebola virus (species Zaire ebolavirus) is the most lethal of 

the 4 viruses that cause EVD in humans. It is highly transmissible and in infected people, it can 

be found in all body fluids. The disease can be quite severe and death can be rapid, occurring 

as soon as 7-10 days after symptom onset. In survivors, the virus has been known to persist in 

immuno-privileged sites and in some instances, this has led to continued disease transmission 

and disease recrudescence. In addition, there is no FDA-approved treatment. 

The virus is an international public health threat. It is responsible for the majority of reported 

EVD outbreaks (64%; 18/28) to include the largest EVD outbreak in history in 2014 in West 

Africa. The virus has infected over 31,000 persons and resulted in over 12,000 deaths. On 

August 1, 2018, an EVD outbreak due to Ebola virus (species Zaire ebolavirus) was declared in 

Eastern Democratic Republic of Congo. On July 17, 2019, the outbreak was declared to be a 

PHEIC. On February 12, 2020, the WHO Emergency Committee unanimously agreed that the 

outbreak still constitutes a PHEIC with over 3000 persons infected and over 2000 deaths. The 

current outbreak continues to be classified as a PHEIC. The virus also is a US public health 

threat. There were 11 individuals infected with Ebola virus (species Zaire ebolavirus) treated in 

the US, all of which were associated with 2014 West Africa outbreak. Of these, 9 were infected 

in West Africa and 2 were infected in the US while caring for a returned traveler. Additional 

persons were repatriated to the US following high-risk exposures to confirmed EVD patients

during the 2014 West Africa outbreak and 2018 DRC outbreak, none of whom developed EVD. 

The WG would say “Yes” this virus is a public health threat.

The next question relates to benefits, “How substantial are the desirable anticipated effects of 

vaccination.” One study was evaluated using GRADE that provided data on vaccine efficacy. 

This study demonstrated protective effect from vaccination at the participant level with a 96% 

risk reduction (RR:0.04 [95%CI: 0.0001 – 0.74]). Therefore, the WG determined that the 

anticipated effects are “Large.”

With regard to harms, the question is, “How substantial are the undesirable anticipated effects?” 

From the GRADE analysis, it is known that arthralgia is more commonly reported among 

vacinees (RR: 2.55). Severe arthralgia is more commonly reported among vaccine recipients, 

although it seems to be uncommon (RR: 6.40). Arthritis is also more commonly reported among 

vacinees (RR: 1.80). Pregnancy loss in vaccinated women does not seem to be significantly 

higher than in non-vaccinated women (RR: 1.35). However, the data are limited for this 

outcome. It also is known that rVSV vaccine virus has been detected post-vaccination in blood, 
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

31

saliva, urine, and synovial fluid and that vaccine-related SAEs are rare. The WG determined the 

undesirable anticipated effects to be “Moderate.”

The question regarding the balance of benefits and harms is, “Do the desirable effects outweigh 

the undesirable effects?” To make this determination, the WG considered the demonstrated

efficacy of the vaccine, the high severity of illness in people who contract the disease, the high 

transmissibility of the virus in infected individuals, the issues of virus persistence demonstrated 

by instances of continued disease transmission and disease recrudescence, the lack of an FDAapproved treatment, and that vaccine-related SAEs are rare. Based on these considerations, 

the WG thinks that it “Favors Intervention.”

With regard to the overall certainty of effectiveness of the vaccine, one study evaluated using 

the GRADE process demonstrated protective effect from vaccination. At the participant level, 

the overall certainty in the evidence for effectiveness is “Moderate.”

Regarding the overall certainty for evidence of safety, several outcomes in the GRADE analysis 

were related to safety. The first was arthralgia (0-42 days). Arthralgia is more commonly 

reported among vaccine recipients compared to placebo. The certainty level for this evidence 

was “Very Low.” Low certainty may be due to the variability among the studies included in the 

evaluation in terms of the definition of arthralgia, evaluation of arthralgia, availability of 

specialized care/radiographic imaging, and timing at which arthralgia was ascertained. 

In terms of the outcome of severe arthralgia, severe arthralgia is more commonly reported 

among vaccine recipients compared to placebo or unvaccinated, but overall appears to be 

uncommon. The certainty of evidence is “Low” or “Very Low” depending upon whether the 

studies were RCTs or observation. Again, low certainty may be due to variability between 

studies in the evaluation of arthralgia and timing at which arthralgia was ascertained. 

With regard to post-vaccination arthritis (0-56 days), arthritis is more commonly reported among 

vaccine recipients compared to placebo. It also is known that the rVSV vaccine virus has been 

detected by RT-PCR in the synovial fluid of 4 vaccinated participants. The certainty of evidence 

is “Low” or “Very Low” depending upon whether the studies were RCTs or observation. Again, 

some of this may be due to variability between studies in the definition of arthritis, methodology 

used to diagnosis arthritis, availability of specialized care/radiographic imaging, and timing at 

which arthritis was ascertained. 

Concerning vaccine-related adverse pregnancy outcomes, pregnancy loss among vaccinated 

pregnant women was not significantly higher than pregnancy loss among unvaccinated 

pregnant women. The certainty of this evidence is “Very Low.” 

Regarding vaccine-related SAEs, across 12 studies and over 19,184 vaccinated individuals, 

there were 2 vaccine-related and 1 possibly vaccine-related SAEs (anaphylaxis, febrile reaction, 

influenza-like illness). All of these resolved without sequelae. The certainty of evidence is “Low”

due to extraction of vaccinated-arm data only, which rendered the data observational, and that 

vaccine-related SAEs are rare. 

Pertaining to transmissibility of vaccine virus, no data are available on vaccine virus 

transmissibility to non-vaccinated persons or animals. Viral dissemination and shedding were 

assessed as an indirect surrogate for this outcome. The certainty of evidence is “Very Low” as 

outcome data were collected only from the vaccinated study arms, thus rendering the data 

observational. 
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

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In summary, the overall certainty of the evidence in terms of the safety of the intervention was 

determined to be “Very Low.”

The next question relates to target population sentiment, “Does the target population feel that 

the desirable effects are large relative to undesirable effects?” No Knowledge, Attitudes, and 

Practices (KAP) surveys have been conducted amongst the 3 populations of interest for this 

subject. The WG had several discussions about this and the feeling was that persons 

responding to EVD outbreaks and HCP at federally-designated ETCs will likely think the 

desirable effects outweigh undesirable, given that several of them have enrolled in the 

PREPARE clinical trial that is offering the vaccine. In addition, the majority (10/11) of the 

EVD patients treated in the US were either responding to an EVD outbreak and/or were HCP.

Response to vaccination has been mixed among BSL-4 personnel. Some enrolled in the 

PREPARE clinical trial that is offering the vaccine, so there are people who are open to 

vaccination. Others have wanted to enroll in PREPARE, but have been unable to do so because 

of logistical challenges. There are currently only 3 clinical sites for the PREPARE trial in North 

America located at NIH, Emory University, and Winnipeg. However, people have expressed 

interest in accessing the licensed vaccine when it is available outside of the 3 PREPARE clinical 

trial sites. There are anecdotal reports of some people declining to be vaccinated because they 

felt that the additional level of protection afforded by vaccination, in the backdrop of strict 

biosafety measures already in place in BSL-4 laboratories, was considered to be minimal 

compared to the potential undesirable effects of vaccination. The WG determined that this 

“Varies” among the 3 different populations.

The second question regarding target population sentiments is, “Is there important uncertainty 

about or variability in how much people value the main outcomes?” Again, the WG feels that 

individuals responding to an EVD outbreak and HCP at federally-designated sites will likely think 

that the desirable effects are large relative to undesirable effects. Among the BSL-4 population, 

there was a mixed response to vaccination. However, the WG thinks that amongst BSL-4 

laboratorians and support staff, most think the desirable effects are large relative to undesirable 

effects. For this question, the WG made the determination that there is “Probably no important 

uncertainty or variability.”

The question with regard to key stakeholder sentiments is, “Is the intervention acceptable to key 

stakeholders?” Again, no KAP survey data are available. The WG feels that for the majority of 

the 3 populations of interest, the vaccination is acceptable. NGOs, federally-designated ETCs, 

governmental organizations, and BSL-4 laboratories have been supportive of staff receiving the 

vaccine through the PREPARE clinical trial. Therefore, the WG answered “Yes” to this question.

The question regarding resource allocation is, “Is the intervention a reasonable and efficient 

allocation of resources?” A cost-effectiveness evaluation was not performed as this vaccine is 

intended for use in preparedness scenarios in limited populations and not as routine vaccination 

in the general population. At this time, the vaccine will be stored and made available through the 

US government. Therefore, the WG answered “Yes” to this question.

The question pertaining to feasibility is, “Is the intervention feasible to implement?” As it appears 

now, licensed vaccine will likely become available by the third or fourth quarter of 2020. The 

vaccine is currently available through the PREPARE clinical trial. There are ongoing discussions

to identify mechanisms to allow for limited quantities of investigational-labeled vaccine to be 

made available for ACIP-recommended populations in the interim period between ACIP
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

33

recommendations and availability of licensed product outside the setting of a clinical trial. 

Therefore, the WG answered “Yes” to this question.

Regarding the balance of consequences, the WG made the determination that “desirable 

consequences probably outweigh undesirable consequences in most settings.”

The question related to the sufficiency of information is, “Is there sufficient information to move 

forward with a recommendation?” To make this determination, the WG considered that there are 

available efficacy data in an outbreak setting, as well as safety data for 19,184 persons 

vaccinated in the US, Europe, and Africa that has been evaluated using GRADE. Therefore, the 

WG answered “Yes” to this question.

Discussion Points

Dr. Romero requested additional information regarding the duration of the arthralgia or arthritis

that presented in these patients. 

Dr. Cossaboom responded that in general, most of the arthralgia events reported were mild and 

resolved over a short period of time. There were instances of arthralgia that persisted for more 

than a month, and also resolved then recurred.

Dr. Talbot observed that the studies were conducted in healthy populations, which she assumed 

meant immunocompetent. She wondered whether anything was known about other comorbid 

conditions such as whether the vaccine would be safe for someone who has severe heart 

disease, and what constitutes the definition of “healthy.” She emphasized the importance of 

having a standard definition for providers.

Dr. Frey did not think they had those data. The vaccine is being recommended for and 

presumably being given only to people who are otherwise healthy and not pregnant. She was 

not sure the WG had defined what “healthy” means. For clinical trials, the definition is usually 

pretty strict. They can look at the definition used in the PREPARE trial. The definition would 

likely differ in the US from international populations. In the US, “healthy” typically means without 

most comorbidities. Some studies allow issues such as hypertension if it is well-controlled. 

Certainly, non-pregnant and non-lactating women would be allowed.

Regarding Outcome 4 concerning arthritis, Dr. Szilagyi inquired as to whether patients were 

followed longer than 56 days, which would be an important measure. Also, the incidence rates 

for arthritis in Outcome 4 were 2.2% versus 2.1%. That does not calculate to a risk ratio of 1.8. 

He suggested checking those numbers. He wondered whether the vaccine supply would be 

large enough if there were to be a large outbreak, and if the WG planned to address this.

Dr. Cossaboom reiterated that there was considerable variability in the methods that were used 

to follow-up and clinically diagnose arthritis. Some of the references did follow-up patients for 

more than 56 days. There were few reports of recurrent arthritis and durations of longer than 56 

days.

Dr. Romero asked whether individuals were screened for pre-existing arthralgia or arthritis 

conditions and, if so, whether those individuals were at greater risk.
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

34

Dr. Coller (Merck) indicated that long-term follow-up for arthritis and arthralgia was included in 

many of the studies during which the subjects continued to be followed out for at least 6 months 

in the US-based study. There were some recurrences as was alluded to for arthritis events, 

including issues such as trigger finger, that were observed out even 2 years in the Geneva 

cohort. Based on the limited sample size, she thinks they do have a reasonable view of the 

duration and recurrence of arthritis events. 

Dr. Poehling inquired as to whether the data on transmissibility were based on the PCR studies. 

Since the backbone is a VSV, she also wondered what the incidence of stomatitis is in the 

vesicular outbreaks.

Dr. Cossaboom indicated that there were no data available on transmissibility of the vaccine 

virus, so the WG decided as a surrogate to assess the detection of vaccine virus by RT-PCR in 

blood, saliva, and urine. For the purpose of the presentation, the WG did not do a 

comprehensive systematic review on the outcomes of incidence of the oral and skin lesions 

because those were lower in importance to the WG. However, they do plan to address this in 

the future.

Dr. Cohn requested that Dr. Coller remind them of the overall incidence for arthralgias was and 

what proportions of the persons who had arthralgia had longer-term, greater than one week or 

recurring events.

Dr. Coller (Merck) indicated that the overall incidence of arthralgia across the program, specific 

from the US prescribing information, is that approximately 10% to 15% of individuals develop 

arthralgia. Typically, that resolves within the first 7 days or so. She will look up and report back 

to ACIP the proportion of persons among whom arthritis or arthralgias resolves and the 

proportion in which they are long-term.

Dr. Sanchez asked whether arthritis or arthralgia had occurred in the other vaccines for which 

the VSV has been used.

Dr. Choi said that she read other papers on this, which did not seem to find that. In a review 

paper that examined other VSV-based vaccines, arthritis was not seen. Arthritis was not seen in 

humans affected by the VSV vaccine, so the initial paper that assessed arthritis and the synovial 

fluid issue in vaccinated individuals postulated that this may be something that is specific to this 

combination of the VSV plus the glycoprotein of the Zaire behaving somewhat differently than 

would have been expected because it was not seen with the VSV in humans or animals.

Dr. Bernstein noted that the patients who had arthralgia did not evolve into arthritis, and 

wondered whether those were the same or different patients.

Dr. Cossaboom replied that in many of the reports, there were individual-level data. There were 

reports of arthralgia and arthritis, but in some cases it was not clear whether they were the 

same people.

Dr. Coller (Merck) added that in many of the cases, it was the same individuals who 

experienced some joint pain and then had evidence of joint swelling. Recalling an earlier 

question about whether there was evidence that a prior joint injury led to an increased risk of 

arthritis and arthralgia, she reported that they conducted an analysis in the large Phase 3 study 

conducted in the US and did find that prior damage to joints and/or being female led to an 

increased risk of arthritis. 
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

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Dr. Fink (FDA) mentioned that in the data that the FDA evaluated in the Biologics License 

Application (BLA) submission, they looked at events of arthritis and arthralgia and found that 

arthritis specifically occurred at a range of 0% to 24% of subjects. In most studies they 

evaluated, the arthritis rate was less than 5%. There was one outlier in a study from Switzerland 

where arthritis occurred at a rate of 24%. That outlier study also had the highest proportion of 

subjects who had prolonged arthritis, which was 6 subjects out of 24.

Dr. Messonnier asked whether the FDA considered pre-existing conditions and if there are any 

that should be contraindications, and if they considered pregnancy categories.

Dr. Fink (FDA) indicated that the FDA did not consider there to be any pre-existing conditions 

for which the vaccine would be contraindicated based on the available data, and considering the 

severity of Ebola disease and the benefit/risk considerations. There were individuals in the 

safety database who had some pre-existing conditions, including human immunodeficiency 

virus (HIV) infection and other immunocompromising states. It is also worth noting that in the 

Ebola Ça Suffit trial, there were no exclusion criteria related to pre-existing conditions other than 

having a medically significant condition that resulted in hospitalization or required treatment for 

Ebola disease. In terms of pregnancy, the FDA labels no longer have pregnancy categories. 

Instead, there are descriptions of data and risk considerations related to human and animal data 

regarding pregnancy. The non-clinical or animal studies that were done to assess for 

reproductive toxicity did not raise any concerns with regard to use in pregnancy. As mentioned 

during the presentation on the GRADE analysis, there are limited data on pregnancy outcomes 

in humans who have been vaccinated. There are not enough data to make any firm conclusions 

about risks from exposure to the vaccine during pregnancy. That being said, considering the 

overall risk and benefit balance, the vaccine indication does include women who are pregnant 

who are at risk of Ebola exposure.

Dr. Schaffner (NFID) pointed out that the emphasis had been on PrEP, but he wondered about 

post-exposure prophylaxis (PEP) If there were to be another episode such as the one in Dallas, 

he imagined there would be great interest in using this vaccine in a PEP circumstance. He 

asked whether the WG had considered PEP.

Dr. Choi indicated that the WG discussions have focused on PrEP and identifying the 

populations at highest risk. In the DRC, the vaccine is used essentially in a post-exposure 

method with the rings and clusters. The WG will continue to address the issue of post-exposure 

and other populations for whom they potentially would suggest recommendations.

Dr. Frey emphasized that the WG still has a lot to discuss, but concentrated this session on the 

3 most urgent groups who needed to be addressed. They will have a lot more to present in the 

coming months.

Dr. Bernstein observed that since pregnancy loss was higher in vaccinees versus nonvaccinees, although not statistically significant and there were limited data, perhaps there would 

be value in objectively identifying that women are not pregnant before receiving this vaccine.
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

36

Dr. Choi indicated that in some of the clinical trials conducted, pregnancy was an exclusion 

criterion. Certainly, there would have to be some precautionary language on that issue.

Dr. Frey emphasized that the WG is just concentrating on the 3 major populations of interest in 

the US, and that there are limited data available. There is a lot of uncertainty about the evidence 

to recommend, so they want to be cautious. They are moving forward with these first 3 groups 

in terms of vaccinating adults 18 years of age and older who are relatively healthy and not 

pregnant. They hope to review more information as more vaccine is administered, particularly 

from the trials that are ongoing. She used the correlate of smallpox and giving Dryvax® or 

ACAM2000® live attenuated viruses, which would be used to vaccinate pregnant women and 

otherwise compromised hosts in an outbreak setting. While the WG was not yet at that point in 

their deliberations, those discussions will be forthcoming.

Ms. McNally asked whether there was any specific information about what concerns the BSL-4 

personnel had who anecdotally indicated that they were concerned about the potential 

undesirable effects of the vaccines.

Dr. Choi responded that some of the BSL-4 laboratory personnel felt that there are other 

precautionary measures in place in BSL-4 laboratories and as such, some of them did not feel 

that vaccination would add that much to the existing protection. At the same time, there are 

people in that population who have been vaccinated through PREPARE and are supportive of 

others being vaccinated. They also heard that there are groups within that population who 

wanted to take part in PREPARE, but could not do so because of their location. Because it is a 

clinical trial, there is a lot of follow-up that has to be done at the clinical trial site. Some people 

were not able to take the time off for that and still be paid, so there were a lot of logistical and 

financial concerns that impeded them from enrolling.

Dr. Frey reminded everyone that the information the WG has from these populations and their 

desire to receive or not receive vaccine is anecdotal. They spoke to some of the supervisors 

and administrators in those areas, who shared anecdotal information. Some people wanted to 

see more safety data after the vaccine had been tested further. A variety of other reasons were 

given as well, but the overall sense from the people who the WG spoke with was that the 

majority of those populations would be interested in having the vaccine available to them. Those 

who had not already received the vaccine or were hesitant about taking it cited that they already 

were doing a good job with existing personal protective equipment (PPE) and preferred to wait 

for additional safety data.

Dr. Cohn requested clarification on what the risk is to BSL-4 laboratory workers in terms of 

whether there ever has been a case of Ebola related to an exposure, or if there have been 

exposures in this population.

Dr. Choi responded that there has never been a case of EVD diagnosed in a BSL-4 worker in 

the US. There was one individual in Russia, who she believes died.

Circling back to the comment about the HCP definition, Ms. Stinchfield (NAPNAP) emphasized 

that hospitals and healthcare settings take that definition very literally. As they saw earlier, it is 

not complete. She cautioned that as they get into lists and policies, they may find themselves in 

trouble. For example, in the Children’s Minnesota policy for proof of immunity to work at the 

hospital, they basically put in the link to the CDC healthcare vaccination schedule. At that site, 

there is a very abbreviated part of the definition that was shown during this session that does 

not included the sentence about “including, but not limited to.” It looks like the professionals 
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

listed there are the professionals to whom that refers, which she did not think was the intent. 

She called everyone’s attention to the National Foundation for Infectious Diseases (NFID) Callto-Action: Improving Healthcare Personnel Immunization Rates written in March 2018. Many of 

the ACIP liaisons participated in the development of that publication and developed a much 

simpler definition, which is, “All healthcare personnel who work directly with patients, or who 

work in any capacity in a healthcare setting, should be vaccinated in accordance with CDC 

recommendations.” The CDC recommendations include the details for specific vaccines. She 

suggested that they work on improving the definition. 

37

Dr. Lee asked whether the groups queried for acceptability were frontline workers handling 

replication competent Ebola virus, or if it was generally anecdotal reports from supervisors. She 

is more concerned about the frontline workers specific to this recommendation category.

Dr. Damon, Director of the Division of High Consequence Pathogens and Pathology (DHCPP) 

where BSL laboratory work occurs at the agency, reported that in the history of the BSL-4 

laboratory work at CDC, there have been no breeches in the use of PPE that would have 

required some sort of PEP or treatment. Most other institutions that have BSL-4 laboratories 

track this very closely and to her knowledge, there is one example in Eastern Europe of an 

exposure in which treatment with an investigational antivirals and post-exposure vaccination 

were used. Dr. Choi described the one episode on Russia where there was exposure. In terms 

of work in a field laboratory setting, CDC ran and operated a laboratory that tested and 

processed tens of thousands of suspect and confirmed Ebola samples and had no breeches in 

exposure and no infections. Several of CDC’s personnel had been vaccinated prior to going to 

work in that laboratory through one of the investigational protocols.

Dr. Frey asked Dr. Damon to explain to ACIP if it is the policy to vaccinate workers, if a vaccine 

is available, prior to them working in BSL-4 laboratories. 

Dr. Damon responded that this decisions would be made with occupational health with the 

scientific program to understand the level of risk and the additional benefit versus risk that would 

be associated with any individual vaccine. There is not a requirement for anthrax vaccination in 

CDC’s laboratories as it is BSL-3, but there is a requirement for smallpox vaccination among 

BSL-4 laboratory workers. The smallpox decision was made because there is no disease 

anywhere in the world, so the potential risk for an undiagnosed exposure led to that 

recommendation. With the additional barriers available to prevent infectious exposure with 

Ebola within the BSL-4 laboratory and training of the personnel, this would likely be an individual 

decision that should be made in concert with the scientific program and occupational health to 

judge the level of risk. Certainly, people handling animals and infected animals are likely at 

higher potential risk than others. Understanding people’s level of risk in terms of the potential for 

an arthritis is important, given that it could be debilitating for a number of days. BSL-4 personnel 

carry around an additional 5 to 10 pounds of weight in terms of the suit and breathing 

apparatus, so mobility is already less than what it is like to walk around in in a normal 

environment.

Ms. McNally emphasized that as reported during this session, no KAB surveys have been 

conducted among the 3 populations of interest and the anecdotal reports indicated concern 

regarding the arthritis/arthralgia or the potential vaccine-related events from pregnancy 

outcome. She requested that someone flesh that out further.
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

38

Dr. Choi recalled that the concerns were mostly related to arthritis/arthralgia and reactogenicity 

associated with the vaccine. She did not recall a WG discussion specifically about concerns with 

pregnancy.

Dr. Hunter thought they had discussed 2 fairly well-defined population thus far, the BSL-4 

laboratory personnel and people who work in a federally-defined Ebola Treatment Center. 

However, the other groups is somewhat less well-defined and could include volunteers in NGOs 

and others who are deploying in various capacities who will have various levels of risk. 

Consideration should be given to the level of risk, where someone is on the ring, and how much 

risk there is of death depending upon whether someone is out in the bush in West Africa and 

cannot get a medivac because transportation is breaking down, someone is in a regional center 

away from the outbreak and may not have direct contact with patients based on the assignment, 

or someone is on their way and may or may not have exposure depending upon length of stay. 

There is going to be a lot of interesting conversation about risk for dying versus risk for 

arthralgia. He assumed that the simple policy statement that “it is recommended” is going to 

have a lot of information in the guidance for various levels of risk upon which ACIP is not going 

to vote.

Dr. Choi said that the WG agrees. They kept the definition somewhat broad. Initially, it was 

“persons deploying to an outbreak.” However, they felt that on some level that was limiting. As 

mentioned, someone was repatriated during the current outbreak because of a high-risk 

exposure. That is a US personnel who is in the DRC and normally works at a hospital in the 

DRC. He had contact because a pregnant Ebola patient presented to his facility whom he took 

care of. That is why they left out the word “deployed.” There are oftentimes NGOs and other 

organizations working in places where the Ebola outbreak hits. If the language is limited to 

“deployed,” it potentially puts them out of the box though they could be at risk depending upon 

transmission in the community.

Dr. Cohn pointed out that they would be voting on the language in the recommendation in terms 

of these groups. However, there will be additional guidance in the Policy Note that is being 

written about how to assess persons at risk and guidance for these organizations. This is going 

to be a very risk-based assessment not only for laboratory personnel, but also for all of these 

groups. There also will be guidance about groups who should not be vaccinated.

Dr. Bell indicated there are a number of consultants on the WG, some of whom in Europe are 

already vaccinating their responders and have developed some clear vaccination guidelines 

targeted to the types of settings their workers may encounter. The WG anticipates something 

similar that would appear in the Policy Note as Dr. Cohn indicated. The point is every well-taken 

in that there are all sorts of exposures that may be particular to specific types of organizations 

and they will have to work through that very carefully.

Dr. Frey noted that if ACIP decided to recommend this vaccine, an ACIP recommendation 

would not make it mandatory for people to be vaccinated. She appreciated the fact that when 

particular organizations read that ACIP recommends a vaccine, that automatically translates to 

a mandate to be vaccinated. That is not the case, and a lot of guidance would be given for how 

those decisions should be made. It would be up to organizations to determine the risk for their 

particular employees. There are so many different individual situations that could occur, the 

decision-making needs to occur at the level of employment.
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

39

Dr. Cohn asked whether there has been any discussion about an upper age limit in terms of a 

recommendation or information about use of this vaccine in older adults.

Dr. Choi indicated that when the WG reviewed the clinical trials, some of them did have an 

upper age restriction that she believed was 65 years. However, the WG has not talked 

specifically about setting an upper limit.

Dr. Frey added that this relates back to the definition of what constitutes “healthy.” As people 

age, they do have a tendency to have morbidity or comorbidities.

Dr. Fryhofer (AMA) said that as a practicing physician and member of this WG, she conveyed 

how much she appreciated the questions that came from ACIP regarding this decision and what 

a fabulous job the two CDC leads have done in looking at this. She said she did not think they 

had slept over the last two months, and expressed gratitude for their hard work.

Dr. Frey reminded everyone that this is a live-attenuated vaccine vector, VSV, in its recombinant 

state. With live-attenuated vaccines come more side effects (fever, myalgias, arthralgias) than 

occur with subunit vaccines, for example. These are frequently not unexpected. In addition, 

there is limited information about transmissibility in terms of this vaccine. While people have 

concerns about transmissibility, this has not been well-studied. There is no evidence for it, but 

there is evidence for skin lesions that have virus in them and other fluids that test positive 

through PCR. The WG recommendations are population-based for this particular vaccine, given 

the mortality related to infection should someone become infected. They are not being 

presented in the sense of shared decision-making. The decision-making processes will be at the 

level of the institution.

 

Dr. Coller (Merck) reported back on some of the questions for which she looked up specific 

responses. In terms of arthritis, data from Merck’s largest double-blind, placebo-controlled, USbased Phase 3 study, approximately 3.7% of subjects developed arthritis who received the 

target dose. The median onset for that was 11 days post-vaccination. The median duration of 

the arthritis was 6 days, with a range from 0.5 to 44 days for the target dose and 0.5 to 156 days 

for the high-dose group included in that study. Nearly all of the arthritis events had resolved 

prior to the 6 months and there were no recurrences out to 2 years. A subset of about 500 

subjects were followed for 2 years out of the total of 1200. For arthralgia, there was a lot of 

variability. It was assessed across all of the trials. In the Phase 1 blinded trials, it ranged from 

10% to 50% versus 22% in placebo. On the US-approved label, that number is 18%. Median 

onset tended to occur quite early, within days, and was generally resolved by Day 14. Some 

went longer than that, but generally resolved by Day 14. As Merck talk about it, the arthralgia 

was generally days to weeks and the arthritis was more weeks extending out to months in some 

cases. 

Dr. Cossaboom added more information with regard to background. The Geneva trial was the 

first to identify arthritis and they provided extensive investigation into the cases. To add on to 

the information Dr. Coller provided, there were 24 cases of temporally associated arthritis in this 

trial out of 102 subjects. The median duration of the arthritis was 34.5 days. The median time of 

onset was 10.5 days. Of the 24 subjects with arthritis, 5 reported recurrent arthritis or arthralgia. 

That had a duration ranging from 3 to 222 days, with a median duration when taken together 

with those recurrent reports of arthritis of 81.5 days. Regarding the question of the risk ratio that 

was reported for Outcome 4, she discovered that there was a small arithmetic error that will be 

updated for the final slides, but it was not significant.
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

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Dr. Damon recalled that there had been discussion at some point about the potential for people 

with cardiac risk factors. She invited their colleagues from the Strategic Advisory Group of 

Experts on Immunization (SAGE) who have been following the WHO efforts to assess safety, 

and from the FDA to discuss what they have seen in terms of any cardiac risk factors or AEs.

Dr. Cravioto (WHO/SAGE) indicated that they have not received any information regarding any 

cardiovascular effects. The main AEs that have been reported in the use of the vaccine have 

been arthralgias. Probably because of the way the vaccination has been done and the follow-up 

difficulties, they have not seen the arthritis problems in that sense. He noted that the Global 

Advisory Committee on Vaccine Safety (GACVS) recently published its newest bulleting that 

includes the entire analysis of safety data for the VSV and Ad26.ZEBOV Ebola vaccines, which 

is available on the WHO webpage. 

Dr. Fink (FDA) indicated that in the safety data the FDA reviewed for the licensure application 

that included approximately 16,000 adult subjects who received the vaccine, there were no 

reported cases of myocarditis or pericarditis specifically. More generally, there was no signal to 

suggest any cardiac toxicity related to the vaccine. 

Work Group Considerations: Proposed Recommendation Text for Policy Options

Mary Choi, MD, MPH

Viral Special Pathogens Branch

Centers for Disease Control and Prevention

Dr. Choi indicated that all of the policy considerations to be presented would be limited to 

vaccination of healthy, non-pregnant, non-lactating adults ≥ 18 years of age. 

The first vaccination policy issue for posed for ACIP consideration pertained to individuals 

responding to an outbreak: 

Should pre-exposure vaccination with the rVSVΔG-ZEBOV-GP vaccine be 

recommended for individuals in the U.S. population responding to an outbreak of Ebola 

virus disease due to Ebola virus (species Zaire ebolavirus)?

Amongst the WG members, the proposal by strong majority was to recommend. The rationale is 

that there is a documented history of infections in outbreak responders, the benefits of 

vaccination outweigh the risk in terms of severe disease and the lack of an FDA-approved 

treatment, and that there is a risk of exposure even with appropriate use of PPE. It is not always 

what someone wears, but how someone wears it and takes it off. The proposed text for the 

population of individuals responding to an outbreak of EVD was:

Pre-exposure vaccination with rVSVΔG-ZEBOV-GP vaccine is recommended for 

healthy, non-pregnant, non-lactating adults 18 years of age or older in the US population 

who are responding to an outbreak of Ebola virus disease due to Ebola virus (species 

Zaire ebolavirus). 
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

41

The second vaccination policy for ACIP consideration involved HCP:

Should pre-exposure vaccination with the rVSVΔG-ZEBOV-GP vaccine be 

recommended for healthcare personnel* involved in the care and transport of confirmed 

Ebola virus disease patients at federally-designated Ebola Treatment Centers in the 

United States?

The WG proposal by strong majority again was to “recommend.” The rationale is that 

operational ETCs with trained and vaccinated personnel is a part of public health preparedness. 

This population is at high-risk of occupational exposure to the virus. Vaccination provides an 

added layer of protection, in additional to other biosafety measures (e.g., personal protective 

equipment, engineering controls, et cetera). The proposed text for HCP vaccination was:

Pre-exposure vaccination with rVSVΔG-ZEBOV-GP vaccine is recommended for 

healthy, non-pregnant, non-lactating adults 18 years of age or older who work as 

healthcare personnel1 at a federally-designated Ebola Treatment Center in the United 

States. 

The third vaccination policy for ACIP consideration pertained to laboratorians and support staff 

working in BSL-4 facilities:

Should pre-exposure vaccination with the rVSVΔG-ZEBOV-GP vaccine be 

recommended for laboratorians and support staff at biosafety-level 4 facilities that 

handle replication-competent Ebola virus (species Zaire ebolavirus) in the United 

States? 

The WG proposal by strong majority was to recommend. The rationale is that BSL-4 

laboratorians and support staff are at high risk for occupational exposure. Also, the vaccine 

provides an added layer of protection in addition to other biosafety measures (e.g., personal 

protective equipment, engineering controls, et cetera). The proposed text for this consideration 

was:

Pre-exposure vaccination with rVSVΔG-ZEBOV-GP vaccine is recommended for 

healthy, non-pregnant, non-lactating adults 18 years of age or older who work as 

laboratorians and support staff at biosafety-level 4 facilities in the U.S. who are at 

potential risk for occupational exposure to Ebola virus (species Zaire ebolavirus). 

Discussion Points

1st Vaccination Policy Issue for Consideration: Individuals Responding to an Outbreak

Dr. Bernstein pointed out that a strong majority is not unanimous.

Dr. Choi confirmed that a strong majority is not unanimous and explained that for each of the 3 

groups, 1 person voted for shared clinical decision-making. All of the rest voted to recommend

and there were no votes not to recommend.

Dr. Romero clarified that ACIP voted and makes recommendations, while the WG may move to 

submit proposed language to be presented to ACIP.
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

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Dr. Bell further clarified that it would be accurate to say that there were no WG members who 

were opposed to some sort of recommendation for each of these groups.

Dr. Bernstein said he was still questioning whether there was value in documenting someone 

not being pregnant before they receive this vaccine. He requested that Dr. Ault comment on this 

as an obstetrician.

Dr. Ault said he thought it would be the same issue as whether someone is healthy or not. 

There is a general principle that live viruses should not be given to pregnant women, so that 

probably would fall under implementation. In terms of implementation, there is an accurate urine 

test to detect pregnancy. 

Dr. Messonnier noted that when the language was discussed in preparation for this policy 

consideration, it clearly had a tenor of being risk-based. Yet, the way the language was 

articulated did not exactly have that same sense of being risk-based.

Dr. Hunter agreed in context that avoiding clinical decision-making for this would be appropriate, 

because the decision is on more of an institutional level. However, occupational health 

recognizes that there are risks and goes through categories of risk. For just the first of the 3 

groups, he suggested inserting a phrase that states “are at high risk for Ebola infection due to 

responding.”

Dr. Lee emphasized the importance of conveying consistently that this recommendation would 

pertain to certain individuals who are at high risk of exposure not only to confirmed infected 

patients, but also their associated infectious materials. This is important from an access 

standpoint for individuals and from a public health standpoint.

Dr. Cohn suggested that to capture the idea of there being a risk-based assessment, perhaps 

the statement could include the language about all of these recommendations applying to 

“healthy, non-pregnant, non-lactating adults ≥ 18 years of age based on a risk-based 

assessment” and then include parentheses in the 3 different groups to attach the risk-based 

assessment and capture all 3 recommendations.

Dr. Eckert (ACOG) expressed concern with excluding pregnant women, because a woman may 

be working in a laboratory or deployed and happen to find herself pregnant in a high-risk 

situation. The data were not compelling that there is an increased risk to safety in pregnant 

women. This is an opportunity to consider language that might be somewhat less exclusionary 

toward pregnant women for this vaccine and in general. It is known if a pregnant woman gets 

Ebola how bad that is.

Dr. Sanchez agreed that the disease is so severe, they should not completely exclude pregnant 

women. It should be left up to the individual to decide, because nothing is done for the fetus 

either in a pregnant woman who develops Ebola.

Dr. Atmar reminded everyone that this is PrEP, so the vaccine would be given electively. Due to 

the relative lack of data in pregnant women, though the available data do not suggest an 

increased risk, because it is elective and in practically in every circumstance can be withheld 

until the woman is no longer pregnant, the WG decided to suggest the recommendation not to 

use it in pregnant women. This adheres to the concept that live virus vaccines are not given to 

pregnant women, and there are not a lot of data. There may be more data from PEP where it is 

administered in pregnant women to try to prevent them from getting a disease to which they 
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

43

may have been exposed. That may be a mechanism by which eventually this could be 

recommended for pregnant women. The WG thought at this time, it would be prudent not to 

include pregnant women. There was some discussion about whether pregnancy tests should be 

done or not. He deferred to his obstetric colleagues on that question. Regarding the question 

about risk, the WG certainly included “at risk” for the BSL-4 laboratorians and other personnel. 

There also was some discussion about people being deployed who would never come in 

contact with patients. But it also was recognized that many times, people who were deployed to 

an area in response to an Ebola outbreak with the original intent not for them to have patient 

contact, things are fluid and they might end up having a higher risk than initially anticipated. This 

is why the WG thought that those responding might be sufficient, and the risk language could be 

couched in the text rather than in this statement. He did not think anyone was necessarily wed 

to the statement, but the discussion was that risk changes or can change once a person is on 

the ground after responding.

Dr. Frey pointed out that if they took out pregnancy, it would follow to take out non-lactating 

women.

Dr. Romero emphasized that it is known that certain antibiotics should not be used in pregnant 

women due to the theoretical risk of joint damage in animal models. This vaccine definitely 

shows evidence of arthritis, so this raises a concern about whether that also would occur in the 

developing fetus.

Dr. Bell noted that it sounded like people were interested in potentially reflecting the concept of 

risk in the language, and that they wanted to balance that with the kind of implementation 

considerations that would be more appropriate in a Policy Note. For example, agencies 

deploying people would have their own occupational health policies. It seemed that there was a 

fair amount of sentiment to add some wording to the language reflecting the fact that this is 

based on potential risk of exposure to infect patients or materials.

Dr. Messonnier said she thought it may just be in the framing. In other recommendations, it is 

not the recommendation language that is meant to be precise. It is the paragraph before in 

which there is an explanation about why the decision was made that would provide more 

context. It seemed that it would be helpful in the paragraph before this language to articulate 

that this is a risk-based decisions. That is not clinical decision-making exactly. It is a risk-based 

decision, and many of the recommendations include that kind of language. 

Dr. Cohn reminded the ACIP members that they would receive a draft of the Policy Note for 

review, comment, and feedback. If they voted to approve the recommendation, there still would 

be plenty of opportunity to provide feedback in how it is framed.

Dr. Frey emphasized that they would be recommending this vaccine only for people who are at 

risk. Because the risk factor makes the decision-making difficult, the WG anticipated providing 

that kind of guidance in the framing to help people make decisions regarding whether someone 

should be vaccinated.

Dr. Hunter appreciated that and was reassured by the commitment to incorporate risk into the 

guidance that goes along with this outside of the actual vote ACIP makes. He remained 

concerned about how recommendations are implemented in institutions in that the main thing, 

and sometimes the only thing, that is focused on it what ACIP actually votes on and the 

verbiage of that. While he was not wedded to having the word “risk” in the recommendation, but 

stressed that point that if the word “risk” did not appear directly in the statement, it could go both 
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

44

ways. An institution may over-interpret or under-interpret and not necessarily take the risk into 

account and just make an administrative decision, which has happened sometimes.

Dr. Wharton asked whether the Countermeasures Injury Compensation Program (CICP) would 

be applicable if the proposed use of this vaccine resulted in significant AEs.

Dr. Rubin (HRSA) indicated that she was awaiting a response to that question and would get 

back to ACIP.

Dr. Cohn suggested that they go through each of the recommendations and then take a short 

break to incorporate the suggestions and language of risk prior to any motions.

Dr. Talbot pointed out that if an occupational health program requires an employee to receive 

the vaccine who then develops an arthritis/arthralgia, that could be problematic for a nurse at 

the bedside, a surgeon, or someone who works in a BSL-4 space suited up. The risk of 

contracting Ebola may be increased further for someone working in a laboratory who develops 

arthritis. It would be very helpful to know that these people who have stepped forward to take 

care of patients and do this research are protected if they do develop an arthritis.

Dr. Romero added that this raised a very good question pertaining to whether the arthritis or 

arthralgia affects large or small joints. It would be helpful to have this information.

Dr. Cohn asked whether anyone from Merck was present who could speak to the type of 

arthritis that was developed.

Dr. Coller (Merck) thought there was both small and large joint involvement, such as trigger 

finger and knee issues. She said she would verify and report back to ACIP.

The language was revised to read as follows, subsequent to which the discussion continued:

Vote #1 Revised Proposed Language: Pre-exposure vaccination with rVSVΔGZEBOV-GP vaccine is recommended for healthy, non-pregnant, non-lactating adults 18 

years of age or older in the U.S. population who are responding to an outbreak of Ebola 

virus disease and are at potential risk for exposure to Ebola virus (species Zaire 

ebolavirus). 

Dr. Sanchez said he still would prefer that “non-pregnant” be removed because the way it was 

written, it was almost like the non-pregnant woman would not receive the vaccine under any 

circumstances. However, it is a risk and if a woman is at high risk for whatever reason this 

should be an option.

Dr. Frey reminded everyone that they were talking about pre-exposure and that she understood 

that there was concern about the difference between pre- and post-exposure. Typically, postexposure is a higher risk. She said if she understood the FDA comment earlier, pregnant 

women or people with comorbidities potentially could be vaccinated. She emphasized that the 

WG’s recommendation was only for pre-exposure. Given the limited data available, the WG 

feels more confident making this particular recommendation. Certainly, if there are major 

outbreaks or overwhelming cases and people are exposed who are pregnant or potentially 

pregnant, that consideration would be swept away perhaps.
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

45

Dr. Cohn asked whether everyone would be more comfortable if they paralleled this 

recommendation to other immunization recommendations in which they do not include nonpregnant, non-lactating adults, vote on the recommendation, and then have a contraindication to 

state that it is not recommended for pregnant or lactating women.

Dr. Sanchez said that was his point. He thought in the discussion it could be stated that ACIP 

does not recommend it, but it can be a personal choice so that if someone is at high risk 

enough, they could receive the vaccine. The way it was worded suggested that a pregnant or 

lactating woman could not get the vaccine even if she wanted it.

Dr. Bell thought there was an argument to be made for making the language parallel to other 

relatively new live virus vaccines.

Dr. Eckert (ACOG) encouraged consideration of taking out “non-pregnant, non-lactating” and 

placing it below simply because this is not the same risk consideration as if someone contracts 

the disease as some of the other live virus vaccines, given that it is so much more harmful to a 

pregnant woman and her fetus. She agreed that it would be good to give the pregnant woman a 

choice. If she finds herself pregnant in a situation where she is at risk of contracting Ebola, the 

fear is that she would lose a choice of whether she could receive this vaccine if the language 

remained as presented.

Dr. Cohn reminded everyone that on the adult schedule, live virus vaccines for pregnant women 

are “do not give” but it is not in the language of the recommendation exactly.

Dr. Frey asked whether they also wanted to remove “healthy.”

Dr. Poehling agreed that they should mimic the other live vaccines in whatever way that has 

been done previously.

Dr. Cohn did not recall that the word “healthy” had been used in prior language, though the word 

“immunocompetent” is used in the zoster recommendations.

Dr. Bahta emphasized that if they were going to use the word “healthy” it needed to be put into 

context to clarify what they mean.

Dr. Frey recalled that Dr. Talbot mentioned that earlier and the WG would look into what a good 

definition would be. Typically, that would refer to people who do not have much in the way of 

comorbidities. Usually, having a slight cold would not necessarily preclude someone from 

receiving a vaccination.

Dr. Hayes (ACNM) suggested that perhaps instead of “healthy” the word “immunocompetent” 

should be used.

Dr. Atmar thought that would be consistent with the way some of the other adult vaccines are 

recommended to different groups, so he was going to propose something similar.

Dr. Sanchez agreed that “healthy should be removed, given that they had no definition for it. 

Someone with diabetes could be healthy.
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

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Dr. Frey said she thought there was a special chart for immunocompetent patients, so they 

could handle it the same way as is done for pregnant women. 

Ms. McNally emphasized that from a consumer perspective, consistency in the 

recommendations is important to lead to a clear understanding of how these recommendations 

work.

Dr. Romero indicated that the WG would continue to work on the wording during the lunch break 

before making a motion and taking a vote.

2nd Vaccination Policy Issue for Consideration: Healthcare Personnel

Dr. Lee noted a discrepancy in the wording in that the handouts provided to ACIP differed from 

the language presented in that it no longer stated, “care and transport of confirmed Ebola virus.”

Drs. Choi and Romero clarified that correct language was in the handout, which would be 

corrected during the break.

Dr. Cohn clarified that this would be persons identified at a treatment facility identified to be at 

risk, not every individual who worked there.

Dr. Hunter observed that perhaps “in the care and transport confirmed Ebola virus” was too 

specific of a risk to mention. Just HCP is not specific enough, but there might be more than care 

and transport that could pose a risk.

Dr. Atmar pointed out that it would be laboratory personnel who would work in there. Whether 

they are considered to be involved in the care directly could be misinterpreted. The intent was 

HCP at risk, which would include all individuals surrounding that patient and his or her clinical 

specimens (those involved in the direct care, those involved in handling samples, those who 

clean the patient’s room, et cetera).

Dr. Choi added that the initial HCP definition had to do with people involved in direct and indirect 

patient care, including support personnel as well.

Dr. Frey added that the patient transport staff would be included in the HCP definition provided 

that includes examples, so “in the care and transport of confirmed Ebola virus” could be 

removed.

The language was revised to read as follows, subsequent to which the discussion continued:

Vote #2 Revised Proposed Language: Pre-exposure vaccination with rVSVΔGZEBOV-GP vaccine is recommended for healthy, non-pregnant, non-lactating adults 18 

years of age or older who work as healthcare personnel1 at a federally-designated Ebola 

Treatment Center in the United States who are at potential risk for exposure to Ebola 

virus (species Zaire ebolavirus). 

Dr. Romero suggested that the same language changes be made for this recommendation as 

made in the first recommendation. 
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

47

Dr. Atmar suggested adding “and” before “who are at potential risk.”

Dr. Duchin (IDSA) noted that a question arose during the break pertaining to revaccination for 

people who have ongoing exposures—not the first responders but the laboratory workers for 

example.

Dr. Frey indicated that there is not enough information to recommend to not recommend 

revaccination. That question and the available data are being studied by the WG and there will 

be a recommendation forthcoming.

Dr. Romero reminded the voting members and audience that the ACIP the right to revisit any 

recommendation as new information becomes available, so they can bring this back again.

Dr. Lee requested clarification that for the federally-designated Ebola Treatment Centers, they 

were speaking specifically about anyone attached to the unit, including environmental services 

and so forth. Looking at the names of the centers, she thinks of the entire institution versus the 

specific unit caring for Ebola patients.

Dr. Choi clarified that this does not mean everyone who works at a facility, given that the 

facilities treat patients other than Ebola patients. It is intended for people specifically working 

with confirmed patients.

3rd Vaccination Policy Issue for Consideration: BSL-4 Laboratorians and Support Staff

Dr. Szilagyi said he liked the wording and thought the phrase “who are at potential risk” should 

be included in the other two recommendations as well—not just in the framing.

Dr. Frey agreed that this would be a nice solution.

The language was revised to read as follows, subsequent to which the discussion continued:

Vote #3 Revised Proposed Language: Pre-exposure vaccination with rVSVΔG-ZEBOVGP vaccine is recommended for healthy, non-pregnant, non-lactating adults 18 years of 

age or older who work as laboratorians and support staff at biosafety-level 4 facilities in 

the US and who are at potential risk for occupational exposure to Ebola virus (species 

Zaire ebolavirus). 

Dr. Romero suggested that the same language changes be made for this recommendation as 

made in the first and second recommendations.

Dr. Sanchez pointed out that the wording “laboratorians and support staff” may be confusing 

since support staff are a different group of people.

Dr. Frey indicated that “support staff” is a catch phrase that specifically would be for people who 

would be at risk of contracting infection. Those types of decisions would be made at the level of 

the institution, which would define who would and would not be at risk.
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

48

Dr. Choi explained that it is not just laboratorians who work with viruses. The laboratories must 

be maintained, so there are people involved in the maintenance of the laboratories who are not 

necessarily laboratorians. If they have to enter a BSL-4 laboratory that at some point contained 

Ebola virus, they certainly could be at potential risk. Therefore, the WG identified them as 

support staff.

Ms. McNally suggested referring to the HCP definition that gives the examples of clerical, 

dietary, environmental services, laundry, security, engineering and facilities management, 

administrative, billing, and volunteer personnel. 

Dr. Frey clarified that the third recommendation focused on BSL-4 laboratories, so this pertained 

to laboratorians and their associated personnel not HCP per se. It was not clear to her how to fit 

HCP in this definition.

Ms. McNally said she understood that, but some of the people identified as support staff in the 

HCP definition were the same and she would like to see consistency in language to the greatest 

extent possible.

Dr. Bahta suggested saying “laboratorians and the associated staff” rather than “support staff.” 

Support to her is someone who is entering data and did not make her think of someone doing 

the housekeeping in that area.

Dr. Atmar suggested “other staff at risk.”

Combined Language for All 3 Populations

Dr. Romero indicated that during the lunch break, the language for the Ebola vaccine 

recommendation was combined into a single recommendation. He indicated that they could vote 

on the language this way, or vote on each recommendation separately.

Dr. Choi explained that the WG looked back at previous language for other live vaccines, and 

found that the terminology used in the recommendation language varied. Therefore, the 

decision was made to defer to the FDA indications that state, “adults 17 years of age or older” 

with the idea of then discussing pregnancy, immunocompromising conditions, and other 

concerns separately in the Policy Note. She presented the following combined option as revised 

for ACIP’s consideration: 

Pre-exposure vaccination with rVSVΔG-ZEBOV-GP vaccine is recommended for adults 

18 years of age or older in the US population who are at potential risk of exposure to 

Ebola virus (species Zaire ebolavirus) and:

– Are responding to an outbreak of Ebola virus disease; or

– Work as healthcare personnel1 at federally-designated Ebola Treatment Centers 

in the United States; or

– Work as laboratorians or other staff at biosafety-level 4 facilities in the United 

States

Dr. Bernstein suggested changing “and” at the end of the first sentence to “because they.”

Dr. Frey made a motion to approve the language with the idea that it will be corrected for 

grammar and punctuation. Dr. Ault second the motion.
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

49

Motion/Vote: Ebola Vaccine 

Dr. Frey made a motion to approve the language for the proposed policy as presented, with the 

idea that the verbiage would be made grammatically correct prior to publication. Dr. Ault 

seconded the motion. No COIs were declared. The motion carried unanimously with 14 

affirmative votes, 0 negative votes, and 0 abstentions. The disposition of the vote was as 

follows:

14 Favored: Atmar, Ault, Bahta, Bell, Bernstein, Frey, Hunter, Lee, McNally, Poehling, 

Romero, Sanchez, Szilagyi, Talbot 

 0 Opposed: N/A

 0 Abstained: N/A

For the public record, Dr. Ault reported briefly on the discussion that occurred during the lunch 

break. There was a Task Force 10 to 15 years ago to address language around vaccine and 

pregnancy as a lead up to the Tdap vaccine and the pandemic occurring at that time. The Task 

Force decided to state the data available and tell people what was known and what was not 

known. That will apply to the Ebola vaccine as well.

Nancy Messonnier, MD 

Center Director

National Center for Immunization and Respiratory Diseases

Centers for Disease Control and Prevention

Dr. Messonnier presented an update on CDC’s Response to Coronavirus Disease 2019 

(COVID-19). She emphasized that over 800 people at CDC are working on this response, and 

that she was pleased to be able to be the person they could spare for a little while to update 

ACIP on what is occurring and respond to questions.

As a backdrop to what is occurring with COVID-19, coronaviruses (CoV) are a large family of 

viruses that cause respiratory illness. They are named for the crown-like spikes on the surface 

of the virus. In general, coronaviruses are a zoonotic disease that is typically spread among 

animals and can sometimes jump to people. There are 7 human coronaviruses (HCoVs). The 4 

more common HCoVs (HCoV-229E, HCoV-OC43, HCoV-NL63, and HCoV-HKU1) are 

associated with a disease spectrum like the common cold. There are 2 other HCoVs (SARSCoV and MERS-CoV) with which everyone may be familiar. The newly identified virus is SARSCoV-2, which causes coronavirus disease (COVID-19).

The more common HCoVs usually cause mild to moderate upper-respiratory tract infections like 

the common cold, but can cause more severe disease such as pneumonia and bronchitis. The 

symptoms are the same as would be expected with a viral upper-respiratory tract infection 

(runny nose, headache, cough, sore throat, fever, general unwell feeling). Laboratory tests can 

be used to diagnose these common HCoVs, but people generally do not test, so they do not 

identify it.

CDC’s Response to Coronavirus Disease 2019 (COVID-19)
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

50

HCoVs spread from an infected person to others through respiratory droplets by coughing or 

sneezing; close personal contact, such as touching or shaking hands; and/or touching a fomite 

(object or surface) that has the virus on it. These commonly occur in fall and winter, but can 

occur year-round. Young children are most likely to get infected. In general, most people will get 

infected at least once in their lifetime. 

COVID-19 was identified in Wuhan, China in December 2019. Amazingly, within a rapid period 

of time of just 2 weeks, it was identified as being caused by a novel coronavirus that was named 

SARS-CoV-2. Early on during the first identification of this outbreak in December 2019, many of 

the patients were reported to have a link to a large seafood and live animal market. As more 

data subsequently became available, it became clear that many patients did not have an 

exposure to animal markets. That is both cases that occurred before the large cluster at the 

market and certainly the cases after, indicating person-to-person spread. Travel-related

exportation of cases was quickly reported and the first US case was identified on January 20, 

2020. CDC is reporting confirmed COVID-19 cases in the US online on the Coronavirus 

Disease 2019 (COVID-19) webpage on the CDC website. These numbers are updated every 

Monday, Wednesday, and Friday.

The global spread of COVID-19 is actually pretty remarkable. As of February 25th, there were 

80,413 confirmed cases. This is a map that Johns Hopkins University publishes online, which is 

helpful in being able to put this to scale. The map depicts the many countries that have cases. 

The majority of cases remain in China, especially in the Hubei Province. Thus far, 2708 deaths 

reported from COVID-19:

As of February 25. Source: https://www.arcgis.com/apps/opsdashboard/index.html#/bda7594740fd40299423467b48e9ecf6

In terms of the US, there are 14 COVID-19 cases. Of those, 12 are travel-related. These are 

individuals who had direct travel themselves to the affected areas in the Hubei Province. The 

other 2 cases are the result of person-to-person spread to close contacts of cases. The total 

number of cases confirmed in the US remains at 14, with 445 patients tested. CDC separates 

out cases among persons repatriated to the US. After the closure of Hubei Province, a large 

number of people were repatriated to the US aboard several airplanes. There are 3 patients with 

COVID-19 associated with those repatriations from Hubei. After the outbreak identified on the 

Diamond Princess Cruise Ship in Japan, a large number of people were repatriated from that 

ship. That has led to 42 cases among Americans in the US repatriated from that cruise ship. 

There are additional Americans in Japan who had an exposure associated with that cruise ship, 
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

51

and there are additional American patients in Wuhan, China who were associated with 

exposures in Wuhan.

A major topic of consideration regards how COVID-19 is spread. Investigations are ongoing to 

better understand spread. What it thought at this time is largely based on what is known from 

other coronaviruses, as well as the epidemiological data being gathered. In general, the 

presumption is that it is spread primarily through close person-to-person contact with respiratory 

droplets. There are some data to suggest that at least some minority of cases are exposed by 

touching a surface or object that has the virus on it and then touching the mouth, nose, or eyes. 

The data available suggest that the early symptoms of COVID-19 are fever, cough, and 

shortness of breath as would be expected from other viral respiratory diseases. However, a 

wide range of illness severity has been reported from mild to severe disease. As seen from the 

numbers, this can result in death. The estimated incubation period is believed to be 2 to 14 

days. In the rush to make sure that everyone throughout the world knows information as quickly 

as possible, there have been some unpublished reports in the lay literature suggesting longer 

incubation periods. The published literature still focuses on 2 to 14 days. Complications can 

include pneumonia, respiratory failure, and multisystem organ failure. Certainly, the deaths that 

have been reported are more common in people with underlying illnesses and on the older age 

spectrum.

In terms of prevention and treatment, there is no specific antiviral treatment licensed for COVID19. A variety of products that are licensed for other reasons are being investigated for their 

potential role in COVID-19 treatment. In general, the same everyday preventive actions are 

recommended that would be utilized for any respiratory disease:

 Wash your hands often with soap and water for at least 20 seconds; use an alcohol-based hand sanitizer 

with at least 60% alcohol if soap and water are not readily available

 Avoid touching your eyes, nose, and mouth with unwashed hands

 Avoid close contact with people who are sick

 Stay home when you are sick

 Cover your cough or sneeze with a tissue, then throw it away

 Clean and disinfect frequently touched objects and surfaces

 

Because there is no specific antiviral treatment, general treatment for patients has been 

supportive care to relieve symptoms and manage pneumonia and respiratory failure. As of that 

morning, the US cases have been/are generally doing well. They are on the less severe end of 

the spectrum and are recovering. However, several have required oxygen.

CDC has a lot of information online about COVID-19. The website is the place where CDC tries 

every day to ensure that the information, guidance, and communication materials are as up-todate as possible. The agency has tried to include information that is helpful to every sector of 

the community, including public facing materials, materials for providers, and materials for public 

health. Information can be located at the following URLs:

 Latest COVID-19 information for the public (www.cdc.gov/COVID19) 

 CDC’s travel health notices (wwwnc.cdc.gov/travel/notices) 
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

52

CDC is recommending seeking medical care if one feels sick with fever, cough, or difficulty 

breathing and have a travel history to China or were in close contact with someone with COVID19 in the 14 days before beginning to feel sick. This is the current definition. It is useful to know 

that of the 12 patients in the US who had travel-associated COVID-19, many returned to the US 

and were asymptomatic upon return. They received information somewhere along their route 

that told them this exact information, they followed it, and were diagnosed with minimal 

exposure to other people. As the disease continues to spread globally, CDC is certainly 

reviewing these case definitions. This is an outbreak for which day-by-day and sometimes many 

times a day, there is new information that CDC is synthesizing and incorporating into the 

recommendations.

In terms of what CDC is doing, a major part of the early strategy is travel recommendations. 

CDC recognizes that any border control strategies are not absolute. The reason for these 

strategies is to try to slow entry of this disease in the US, knowing that the borders cannot be 

sealed off. There was a Presidential Proclamation suspending entry of foreign nationals who 

visited China within the past 14 days into US, exempting immediate family members of US

citizens and legal permanent residents. Enhanced entry screening is being done for anyone 

coming in from China through 11 airports.

There are a variety of travel alerts, which include the following:

Level 3 

(Avoid Non-Essential Travel)

Level 2 Level 1

China Iran Hong Kong

South Korea Italy

Japan

State and local readiness is a key part of any strategy in terms of preparedness and response, 

as it is for everything that CDC does. CDC is dependent upon states for their active monitoring

of health of travelers from China. It is also very important that the state and local health 

departments are pivoting to assess state and local readiness to implement community mitigation 

measures if these become necessary. They are working to identify and mitigate gaps in 

readiness to reduce disease spread while protecting workers, infrastructure, and institutions. 

They are also linking public health agencies and healthcare systems to identify and mitigate 

stressors to the health system. Even if not in a COVID-19 outbreak, these are still activities that 

state and local health departments are already doing. Everything that CDC is doing with states 

is built on eons of preparedness work that has been ongoing in states, as well as at CDC.

Engagement with public health and the healthcare sector is important. CDC engages in calls 

every day with at least some portion of core public health partners, such as the National 

Association of County and City Health Officials (NACCHO), the Council of State and Territorial 

Epidemiologists (CSTE), the Association of Public Health Laboratories (APHL), and the 

Association of State and Territorial Health Officers (ASTHO). They also are speaking with 

multiple subsets of these organizations. There are bi-weekly private sector calls as well. CDC is 

also engaged in governmental outreach including Attorneys General, Mayors, and Governors, 

all of whom have a stake in this effort. In addition, there are multiple conversations with public 

health associations including webinars, podcasts, and conference calls. 
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

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A major part of any strategy to control a disease like this is preparing first responders, 

healthcare providers, and healthcare systems. This is a whole of government effort to: 1) 

establish plans to understand healthcare use and potential surges; 2) develop guidance on 

infection control, hospital preparedness assessments, personal protective equipment (PPE) 

supply planning, and clinical evaluation and management; 3) reinforce infection control 

principles to ensure that the healthcare practitioners who are treating these patients are kept 

safe; 4) leverage existing telehealth tools; and 5) engage supply chain partners to understand 

supply usage and needs. Again, a lot of this information can be found on the CDC website.

If this disease continues to spread globally, it is possible that there will be community spread in 

the US. As the outbreak has surged in the past week, public health has become increasingly 

concerned that at some point in the future, community spread may be seen. It should not be a 

surprise with a respiratory viral disease spreading like this that there might be community 

spread. What they are asking of folks in the community and family readiness space is to start 

preparing for that. While they are not asking anyone to implement changes, they are asking 

them to be prepared so that if these changes need to be implemented, people have already had 

the conversations. CDC is developing business guidance for public and private sectors 

adaptations like telework and flexible sick leave policies. These are the same kinds of things 

CDC worked on in the last influenza pandemic, so they have a head start in doing some of this. 

The agency is publishing guidance for childcare programs, K-12 schools, and colleges and 

universities in case, for example, schools need to be on hiatus at some level. Other countries 

have done this. CDC wants schools, systems, and families to have thought in advance about 

how this might be implemented. CDC is providing planning guides for use by families, 

community- and faith-based organizations, and event planners of mass gatherings. In addition, 

CDC believes that it is important to educate communities about non-pharmaceutical 

interventions (NPIs).

Work has already begun on vaccines on the fastest possible path. There are multiple vaccine 

candidates in the US and globally, including one on which NIH is working. Even as fast as that 

possibly could be, the timeline for that is 12 months—optimistically. This makes it even more 

important to think through NPIs. If there is indeed broader spread in the US and it is necessary 

to implement interventions, social distancing is one of the tools upon which it may be necessary 

to rely. This is why CDC has been pushing folks to think in advance about NPIs.

Discussion Points

On behalf of everyone in the room, Dr. Schaffner (NFID) expressed enormous appreciation to 

Dr. Messonnier for all the she is doing and the leadership she is providing. This resulted in a 

standing ovation for Dr. Messonnier. In terms of testing, Dr. Schaffner conveyed that there is a 

desire in the infectious disease community to assist in the diagnosis of cases as early as 

possible and everyone would love to start testing more frequently than they are able to now.

Dr. Messonnier responded that they should celebrate the successes and admit the places 

where things have not gone as smoothly as they would like. CDC’s partners in China posted the 

sequences of the strain within two weeks of public announcement of the outbreak, which is 

remarkable. CDC scientists were able to rapidly turn that genetic sequencing data into 

diagnostics that were rapidly available in the US under an FDA Emergency Use Authorization 

(EUA). This meant that CDC was able to start testing. The first case in the US was identified 

with that RT-PCR kit. CDC’s desire has been to get this test out to its state and local partners as 

quickly as possible. In doing that and doing the quality control that would be expected of CDC to 

ensure that the test was as perfect as possible, some of the state and local health departments 
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

54

ran into problems in terms of assuring quality control. Only 12 state and local health 

departments are currently using the test. CDC is moving as quickly as possible in very close 

partnership with the FDA to disseminate the test to the rest of the public health laboratories in 

the US. To do what Dr. Schaffner is asking and what everyone wants, commercial availability of 

these kits is key. It is commercial availability that would provide the tool to a clinician who needs 

to test. Certainly, that is everyone’s goal. CDC is working very closely with the FDA to get that 

moving forward. That is why right after CDC grew the virus, they put it at the NIH’s BEI 

Resources Repository on purpose because the agency wants to facilitate commercial 

companies turning the diagnostics into a commercially available product. That is moving as 

quickly as the community can make it move. That is never fast enough, but it is their intention.

Dr. Weber (SHEA) suggested that there are two things he thinks CDC can help with, the testing 

and PPE, including N95 masks and ventilators, so that they can be prepared in case there are 

large numbers of patients. He noted that the University of North Carolina (UNC) has one of the 

world’s experts in coronaviruses, Dr. Ralph Baric. UNC has already developed its own test that 

is sensitive and specific, and has been approved by the county health director, state 

epidemiologist, and the health department. They plan to begin testing using it as a research test 

and sending parallel tests to CDC. This would allow them to treat a person as a suspect case 

and protect their health care personnel and the community pending the CDC test. Based on the 

recent FDA communication, their laboratory directors feel that they are unable to use that test. 

They did develop their own test for SARS, MERS, and 2009 novel influenza. He expressed 

hope that CDC would get the FDA to allow UNC to begin using the test on a research basis until 

CDC pushes their tests out. They do not know what is in the Strategic National Stockpile (SNS). 

They know that for N95 respirators, they need to train people per Occupational Safety and 

Health Administration (OSHA), and train respiratory therapists if ventilators are needed. 

Realizing that it may not be prudent to release all of the numbers about where they are stored 

and how much, it would at least help if states knew what is stored so that they can be prepared 

with trained people if they need that equipment as opposed to reading manuals the day it 

arrives.

Dr. Messonnier responded that FDA has oversight over the diagnostic tests. She inquired as to 

whether the FDA liaison were equipped to speak to that. She emphasized that it was well-heard 

and their FDA colleagues are in lock-step with CDC in trying to resolve this problem. In terms of 

the second question, the SNS is not a CDC resource. It belongs to the Assistant Secretary for 

Preparedness and Response (ASPR), so she could not speak directly to that question. 

However, this issue is a major focus of CDC’s preparedness activities. The importance of PPE 

to protect the healthcare sector is vitally important to CDC. There is guidance on the website 

that focuses on the use side. If they have models of a prolonged outbreak, which they do, there 

is a potential to have supply issues. It really depends upon how long an outbreak lasts and the 

severity. CDC is asking the healthcare sector now to use the CDC guidance to think through 

how they might be sparing of those resources in the eventuality that they might be needed later.

Dr. Fink (FDA) said he wished he was equipped, but the testing is under a different center 

entirely.

Dr. Maldonado (AAP) echoed the sentiments regarding the laboratory tests. Stanford also has a 

PCR that looks pretty sensitive and specific and they are just waiting to be able to use it. The 

reason that is important is that right now, they are doing well even in California where a number 

of people are coming in from the Pacific Rim area. If they think that there may be other places 

where screening needs to be done, there may wind up a surge in the hospital. While they can 

handle this, as with 2009 H1N1 it will be difficult to cohort patients together if it is not clear how 
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

55

to separate them, and this could result in more transmission. Given there is a Level 2 travel 

advisory now for Iran, Italy, and Japan, university students are coming back and people wonder 

whether they should be treated with self-isolation. They are doing that for healthcare workers 

who have returned from South Korea. The question remains whether isolation should be 

recommended for Level 2 and wondered whether updates would be coming soon about what is 

going to occur in Europe.

Dr. Messonnier emphasized that this is proceeding in real-time. It has been only 2 months and 

there is not enough of a track record of this pathogen. Everything they are learning is in some 

ways new. While they can base information on what they have learned from other viruses, 

everything that is being learned must be considered, synthesized, and tracked to determine how 

it impacts the response. Right now, CDC is not recommending that travelers from Italy be 

treated that way because widespread transmission has not been shown. CDC and CSTE are 

struggling together regarding the question of what the definition is for “persons under 

investigation (PUI).”

Dr. Hahn (CSTE) emphasized that things are changing very fast. One discussion regards the 

increasing number of countries being added into the higher levels, which is changing daily, and 

the fact that there is no way public health can track everyone coming back from Europe. It will 

become untenable at a certain point to track travelers. As they all work together, they probably 

will make a plan to have a lower level for other countries as they come on board. Public health 

simply cannot maintain and track those. Very robust conversations are underway with regard to 

moving into Phase 2 of the response and the realization that the virus cannot be kept out. She 

expressed hope that in the next couple of days, there would be some reflections on the CDC 

website about some of the decisions being made.

Dr. Messonnier expressed appreciation for everyone’s support, as many have been planning for 

a pandemic for their entire careers. That planning is exactly what CDC is depending on, and is 

equally depending on all of the sectors of the healthcare community that they have all built 

relationships with and worked with for many years. This is a setting in which it is going to take 

the entire village to be able to respond. They need to prepare for something serious. Of course, 

they are all going to hope that this is not what comes to pass. But, it really is the community of 

everyone that will get the US ready.

Dr. Bernstein stressed that Dr. Messonnier is spearheading a truly impressive effort by CDC in 

such an amazingly short timeframe. The knowledge and experiences from past pandemics 

seem to be helping guide emergency readiness preparation that is making a huge difference in 

informing and educating the public in the US and around the world. He expressed gratitude to 

Dr. Messonnier and the hundreds of CDC personnel for their ongoing job well done. He thinks 

this has only just begun and a lot more will unfold as time goes on.

Dr. Messonnier closed by saying that she happens to be the most visible face at the moment, 

but the entire leadership of the agency is at the table working on this. CDC’s Incident Manager 

is Dr. Dan Jernigan who many know as the Flu Czar. They are drawing upon the entire 

expertise of the agency, so this is pulling everyone in together to make this work.
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

56

Introduction

Robert L. Atmar, MD

Chair, Influenza Work Group

Baylor College of Medicine

Dr. Atmar reminded everyone that during the October 2019 ACIP meeting there was an 

overview of early 2019-2020 season influenza activity; a presentation from Sanofi Pasteur of a 

pre-licensure study of quadrivalent high-dose inactivated influenza vaccine (IIV), Fluzone® HighDose Quadrivalent, which was subsequently licensed by FDA on November 4, 2019; and a 

discussion of a planned systematic review of influenza vaccines for older adults. 

Since October 2019, the WG heard a presentation and discussion of preliminary safety results 

from a comparative study of adjuvanted and high-dose inactivated vaccines among persons 65 

years of age and older; heard a presentation from SeqirusTM of a pre-licensure study of 

quadrivalent adjuvanted inactivated influenza vaccine, FLUAD® Quadrivalent that was licensed

by FDA on February 21, 2020; and discussed selection of efficacy/effectiveness and safety 

outcomes for review of influenza vaccines for older adults. 

The agenda for this session included the following presentations:

 Older Adult (65+) Adjuvanted Quadrivalent Influenza Vaccine (aIIV4) Phase III Trial

 2019-20 US Influenza Surveillance Update

 Interim Estimates of 2019–20 Seasonal Influenza Vaccine Effectiveness against Medically 

Attended Influenza from the US Flu VE Network

 Safety of Adjuvanted vs. High-Dose Inactivated Influenza Vaccines in Older Adults: 

Preliminary Safety Results

 Summary and WG Considerations

Older Adult (65+) Adjuvanted Quadrivalent Influenza Vaccine (aIIV4) Phase III Trial 

Gregg C. Sylvester, MD, MPH

Medical Affairs

SeqirusTM A CSL Company

Dr. Sylvester expressed gratitude for the opportunity to present the results of the pivotal Phase 

III trial evaluating the efficacy of the SeqirusTM adjuvanted quadrivalent influenza vaccine 

(aIIV4), also known as FLUAD® Quad. This vaccine is now licensed in the US for persons 65 

years of age and older. 

In terms of background, MF59® adjuvanted trivalent influenza vaccine (aIIV3) or FLUAD®

Trivalent was licensed based on immunogenicity criteria and has been in use for over 20 years. 

It was first licensed in Europe in 1997 and FLUAD® Trivalent was approved by the FDA in 

November 2015 for US in individuals 65 years of age and older. Several effectiveness studies 

have been conducted with FLUAD® Trivalent and have provided evidence of clinical benefit 

compared to standard influenza vaccines1-4. Because FLUAD® Trivalent was licensed under an 

Influenza
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

57

accelerated pathway with the FDA using immunogenicity results, there was a post-marketing 

commitment to conduct an efficacy trial. SeqirusTM negotiated with the FDA to fulfill this postmarketing commitment with a trial using the quadrivalent instead of the trivalent, which Dr. 

Sylvester presented during this session [1

Mannino S, et al. Am J Epidemiol. 2012;176:527-533; 

2

Van Buynder PG, et al. Vaccine. 2013;31:6122-6128; 3Lapi F, et al. Expert Rev Vaccines. 2019 

Jun;18(6):663-670; and 4

Peabody R, et al. Vaccine. 2019].

The trial was an absolute efficacy study in subjects 65 years of age and older conducted over 2 

consecutive influenza seasons, one in the Northern Hemisphere for the 2016-2017 season and 

the other in 2017 in the Southern Hemisphere. It is important to note that the predominant 

circulating strain during the study period was A/H3N2. Over 6600 subjects were randomized 1:1 

to receive 0.5-mL of FLUAD® Quad or a non-influenza comparator, the combination vaccine of 

tetanus, diphtheria, and acellular pertussis (Tdap/Boostrix®). This was a multi-center study 

conducted in 12 countries (Bulgaria, Colombia, Czech Republic, Estonia, Latvia, Lithuania, 

Malaysia, Philippines, Poland, Romania, Thailand and Turkey).

The study was case-driven. To analyze the results, at least 238 PCR-confirmed cases were 

needed to demonstrate the primary endpoint of the study, which was the efficacy of PCRconfirmed influenza regardless of the match of the virus with the vaccine strain and with a lower 

bound of the 95% confidence limit of >40% as negotiated with Center for Biologics Evaluation 

and Research (CBER). Secondary endpoints included efficacy against strains antigenically 

matched to the vaccine strains for those isolates that were culture-positive with the same lower 

bound of >40%. A subset of participants also were evaluated for immunogenicity in both vaccine 

groups by hemagglutinin inhibition (HI) assay 3 weeks after vaccination. The primary safety 

objective was to evaluate the safety of FLUAD® Quad through the assessment of local and 

systemic solicited and unsolicited adverse events for the entire study period up to one year.

This was a randomized observer-blinded study in which the two treatment groups were wellmatched demographically. The majority were between the ages of 65 and 75 years of age. 

Given the countries where the study was performed, 80% of the subjects self-reported either 

being white or Asian. The comorbidity score is based upon a published paper by Hak et al in 

which a comorbidity score of <50 is predictive of a lower risk of influenza-related complications 

[Hak E, et al. J Infect Dis. 2004 Feb 1;189(3):450-8].

In terms of the subject flow for the study, over 6600 subjects were randomized 1:1 as noted 

earlier to receive 0.5-mL of FLUAD® Quad (n=3394) or Boostrix® (n=3396). Blood samples from 

approximately 2800 subjects were collected at Day 1 to baseline and Day 22 for immunogenicity 

assessment. As mentioned earlier, the primary endpoint was absolute VE against PCRconfirmed influenza due to any strain and the secondary endpoint was Absolute vaccine efficacy 

against culture-confirmed influenza due to strains antigenically matched to the vaccine strains. 

Regarding the immunogenicity results, FLUAD® Quad elicited good HI titers for all strains. 

Between 60% to 85% of the subjects achieved at least a 4-fold rise in titers, and 80% of the 

subjects demonstrated titers of ≥1:40 for HI, which satisfied the CBER criteria for 

immunogenicity for all 4 strains.

In terms of case accrual, there was active surveillance for influenza. All subjects were contacted 

weekly for 6 months or until the end of the influenza season, whichever was longer, to assess 

influenza-like illness (ILI) symptoms. The purpose of the active surveillance was to trigger a visit 

to collect a nasopharyngeal swab at or near the onset of these defined symptoms. Cases also 

were evaluated based on different definitions of ILI, for which the primary study endpoint was “at 
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

58

least one respiratory and at least one systemic symptom” and the secondary endpoint was 

“>37.2 °C + cough/sore throat.” These two definitions were included as part of the protocol. Two 

additional definitions were added post-hoc: “≥37.8 °C + cough/sore throat” and “>38°C + 

 cough.” The main differences between these definitions were the subject’s temperature and the 

presence of symptoms more specific for influenza moving from the primary and secondary 

endpoints through the two post-hoc definitions.

In terms of the ILI case accumulation for each of the 4 definitions, moving from the primary, 

secondary, and post-hoc analysis definitions, the number of ILI cases decrease. However, the 

proportion of those cases that were PCR-confirmed increases—less sensitive, but more specific 

for influenza. It is interesting to note that the number of cases that were similar to the vaccine 

strain were less than 10%, meaning that 90% of the cases were dissimilar to the vaccine strain.

Regarding the primary endpoint of the study, PCR-confirmed influenza regardless of strain. The 

protocol-defined ILI definition showed an efficacy of about 20% with the lower bound of the 95% 

confidence interval at >40%, which is a non-significant result per CBER criteria. As the ILI 

definitions increases in specificity for influenza, the efficacy increases up to 50%. For strains 

similar to the vaccine, the range of the VE was much higher at 50% to 75%. With so few cases 

that matched the vaccine strains, the confidence limits are extremely wide and it is necessary to 

be cautious about drawing inferences from these data.

In terms of safety, local AEs were recorded within the first week. The FLUAD® Quad arm had 

higher rates compared to the Boostrix® Tdap arm. These events were mostly mild to moderate 

and self-limited. The most commonly reported local solicited AE was injection site pain. 

Administration of FLUAD® Quad also was associated with higher rate of frequency of the 

systemic solicited AEs within the first week of the study compared to the control vaccine. The 

most frequent reported systemic AEs in both groups were headache, fatigue, myalgia, and 

arthralgia. Severe systemic solicited AEs were uncommon and varied between 0% to 1.1% of 

subjects in the FLUAD® Quad group and 0.2% to 0.6% of subjects in the Boostrix® group.

During a 1-year follow-up, there were no differences between the vaccine groups and the 

percentage of any of the unsolicited SAEs, unsolicited AEs leading to death, unsolicited AEs 

leading to premature withdrawal from the study, any new onset of chronic diseases (NOCD) and 

adverse events of special interest (AESI). Two subjects reported SAEs that were assessed to 

be related to the study vaccine, one with rheumatoid arthritis (RA) in the FLUAD® Quad group 

and the other with a mild cardio infarction in the Boostrix® Tdap. The RA case was assessed by 

the investigator to be related to the study vaccine. There were no deaths related to the vaccine.

As mentioned earlier, the primary endpoint of the study (PCR-confirmed influenza) showed a VE 

of 20%, a non-significant result. As the ILI definition became more specific, including higher 

levels of temperature, the efficacy increased up to 50%. To provide some context to these 

results, Dr. Sylvester shared VE data during the time period this study was conducted. There 

have been multiple published test-negative design studies from the Northern and Southern 

Hemispheres showing fairly low VE in subjects 65 years of age and older at about 20% against 

all strains. In Europe, overall VE was 38% and VE in those 65 years of age and older was 23%. 

In the US, overall was 40% and in those 65 years of age and older was 20%. In Australia, 

overall was 33% and in those 65 years of age and older was -12%.

With regard to the study limitation, the study was relatively short at a little over a year over the 

two seasons and was dominated by H3N2 circulating strains. There was a wide range of 

circulating antigenically and genetically different strains of influenza A/H3N2. As noted earlier, 
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

59

over 90% of the culture-confirmed influenza isolates were antigenically different from the strains 

in the vaccine. In the demographics, the study population was relatively healthy.

In conclusion, FLUAD® Quad elicited a robust immune response for all 4 strains, satisfying the 

CBER criteria for immunogenicity. The FLUAD® Quad VE results were 19.8% to 51% depending 

upon the ILI definition and symptomatology. FLUAD® Quad had an expected and acceptable 

tolerability profile similar to FLUAD® Trivalent vaccine. FLUAD® Quad received FDA licensure 

on February 21, 2020. 

Discussion Points

Referring to Slide 15 and the increasing efficacy, Dr. Talbot said her suspicion was that the 

increasing temperature requirement was dropping off the old of the old. In addition, she noted 

that Slide 26 appeared to refer to the world’s circulation, and wondered what the SeqirusTM

sequencing data looked like.

Dr. Sylvester said that others have made this observation. They looked at the difference in the 

two age groups to see if there was a difference, but there was not. He indicated that Slide 26 

was his back-up slide and is larger data, not US data. Regarding the SeqirusTM sequencing 

data, they showed only 10% matching so they do have a wide variety. However, he did not have 

a graph similar to the back-up slide for the world circulation. While he did not have any clinical 

quantification with him, he indicated that he would find out whether his clinical colleagues could 

provide that.

Dr. Atmar asked whether the patient with RA in the FLUAD® Quad group was in the 

immunogenicity subgroup and, if so, whether the pre-vaccination sera were evaluated for 

markers of RA.

Dr. Sylvester responded that the diagnosis was made 7 months and 1 week after the individual, 

a white male 65 years of age, received the vaccine. He will check to find out whether this patient 

was part of the blood drawing group.

Dr. Whitley-Williams (NMA) observed that it was disappointing that there were almost no African 

American or Black populations involved in the study. Given the diversity of this country, the 

persons who would be eligible for this vaccine, and the health disparities that exist, particularly 

with influenza vaccine and complications, it is disappointing that there were not efforts to include 

more of the Black population.

Dr. Sylvester agreed and indicated that moving forward, they are trying to elicit either countries 

or populations in the US to be able to have a representative sample.

2019-20 U.S. Influenza Surveillance Update

Lynnette Brammer, MPH

National Center for Immunization and Respiratory Diseases

Centers for Disease Control and Prevention

Ms. Brammer presented surveillance data from the 2019-2020 influenza season, which was 

another busy and unusual influenza season. The update she provided represented date through 

Morbidity and Mortality Weekly Report (MMWR) Week 7, which was the week ending February 

14, 2020. Based on information from US clinical laboratories, influenza B viruses were 
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

60

predominant early in the season and influenza A viruses increased as the season progressed. 

As of Week 7, 29.6% of specimens during that week were positive for influenza and 63.5% were 

influenza A viruses. Based on the more detailed data from US public health laboratories, 64.9% 

reported were influenza A during Week 7. That proportion has been increasing. For the season 

overall, influenza A was a little over 50%. Among the influenza A viruses during Week 7, 96% 

were influenza A(H1N1)pdm09 viruses. For the season overall, that proportion is 91%. Among 

the influenza B viruses, the vast majority have belonged to the B(Victoria) lineage at 98%.

Outpatients visits for ILI went above baseline for the first time during the week ending November 

9, 2019 and have been above baseline for 15 weeks. There have been 2 peaks. The first 

occurred during the last week of 2019, with 7.1% of patient visits being for ILI. The second

slightly smaller peak occurred during Weeks 5 and 6, which were the last week of January and 

first week of February when 6.7% of patient visits were for ILI. Based on the state-level ILI data 

for Week 7, 44 states, New York City (NYC), and Puerto Rico (PR) were still experiencing high 

levels of ILI similar to the previous week and only 1 state lower than the peak during Week 5. 

There was a lot of ILI.

Looking at the overall hospitalization rate, during Week 7 that cumulative rate had risen to 47.4 

influenza laboratory-confirmed hospitalizations per 100,000 population. Compared to other 

years, it is higher than some but not particularly high at this point. The rate of hospitalizations for 

persons 65 years of age and older was 116.7, which is relatively low compared to other 

seasons. However, the picture is very different for children. Among children 0 to 4 years of age, 

the cumulative rate thus far is 72.5 per 100,000. This is above what was observed at the end-ofseason for both 2017-2018 and 2018-2019 and just below the same week during the second 

wave of the 2009 pandemic. Children 5 to 17 years of age were higher than any other seasonal 

influenza season at this point in time and approaching the 2017-2018 and 2018-2019 end-ofseason rates, but still well below the pandemic rate.

Adults 18 to 49 years of age also have relatively high hospitalization rates. Their rate for Week 7 

is higher than for any other seasonal influenza season, but is still somewhat below the 2017-

2018 season, which was their high season. Adults 50 to 64 years of age are starting to look 

more like adults 65 years of age and older, with hospitalization rates well below the 2017-2018 

and 2018-2019 seasons.

In terms of pneumonia- and influenza-associated mortality from the National Center for Health 

Statistics (NCHS), pneumonia and influenza mortality has been relatively low this year. Mortality 

has been above the threshold for only 3 weeks, and the amount above the threshold has been 

fairly small. The peak thus far was 7.5% during the first week of 2020 compared to the threshold 

of 7.0%. However, looking at influenza-associated pediatric deaths, the picture is different. Thus 

far this year, there have been 105 influenza-associated pediatric deaths. Unfortunately, it does 

not look like the rate of reporting of those deaths is slowing at this point. Among children for 

whom CDC has information, 72 of those deaths were due to influenza B viruses. All 12 that 

were lineage tested belonged to the B(Victoria Lineage). There were 33 influenza A deaths. Of 

those, 19 that were subtyped were H1 and 1 was subtyped as H3. Typically, about 20% of these 

children are vaccinated against influenza. This year is running about the same or somewhat 

lower.
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

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With regard to impact overall, this is CDC’s second year of providing weekly burden estimates 

as the season progresses. Between October 1, 2019 and February 15, 2020, CDC estimates 

that there have been at least 29 million influenza illnesses, 13 million medical visits for 

influenza, 280,000 hospitalizations, and at least 16,000 deaths due to influenza.

Regarding the viruses that have circulated this season, all 563 influenza A(H1N1)pdm09 viruses 

tested belong to genetic group 6B.1A. There is some genetic diversity within this subclade. All 

74 A(H1N1)pdm09 viruses antigenically characterized using a HI assay with ferret antisera were 

similar to the cell culture-propagated A/Brisbane/02/2018-like reference virus representing the 

2019-20 Northern Hemisphere vaccine component. Of the influenza A (H3N2) viruses, 365 of 

381 (95.8%) belong to the 3C.2a1 subclade and 16 (4.2%) belong to the 3C.3a clade. This was 

the clade that emerged last season and became predominant by the end of the season. 

Although the majority of the viruses belonged to the 3C.2a1 subclade, 31 of 72 (43.1%) of the 

A(H3N2) viruses antigenically characterized by FRA were well-inhibited by ferret antisera raised 

against A/Kansas/14/2017 (3C.3a), a cell-propagated reference virus representing the A(H3N2) 

component of 2019-20 Northern Hemisphere influenza vaccines.

Two genetic groups of B/Victoria lineage viruses are co-circulating, V1A.1 and V1A.3. Of the 

B/Victoria lineage, 50 of 655 (7.6%) viruses belonged to the V1A.1 subclade, which is the virus 

with a 2-amino acid deletion. The remaining 605 belonged to the V1A.3 subclade, which had a 

3-amino acid deletion. The B/Colorado/06/2017 reference virus representing the B/Victoria 

lineage virus in the 2019-2020 Northern Hemisphere vaccines belongs to the V1A.1 subclade. 

Again, even though the majority of the viruses are in a different genetic group from the vaccine, 

53 of 88 (60.2%) of the B/Victoria lineage viruses antigenically characterized by HI using ferret 

antisera were similar to the cell-propagated B/Colorado/06/2017-like V1A.1 reference virus. This 

again indicates that there is cross-reactivity between these genetic groups among the B/Victoria 

similar to the H3N2 viruses.

All B/Yamagata lineage viruses tested belong to a single genetic group, Y3, of which very few 

were seen this season. All influenza B/Yamagata-lineage viruses antigenically characterized are 

similar to cell-propagated B/Phuket/3073/2013 (Y3), the reference vaccine virus representing 

the influenza B/Yamagata-lineage component of the 2019-2020 Northern Hemisphere 

quadrivalent vaccines.

The WHO Consultation on the Composition of Influenza Virus Vaccines for Use in the 2020-

2021 Northern Hemisphere Influenza Season is taking place February 24-28, 2020. That will be 

announced on February 28th and will be followed on March 4, 2020 by a meeting of FDA’s 

Vaccines and Related Biological Products Advisory Committee Meeting (VRBPAC), who will 

make the US-specific recommendations for next season’s vaccine.

In summary, influenza activity remains elevated. Influenza B/Victoria lineage viruses

predominated early in the season, but A(H1N1)pdm09 viruses have increased in recent weeks. 

For the season overall, approximately equal numbers of B/Victoria and A(H1N1) have been 

reported. Overall severity has been low, but hospitalization rates among children and young 

adults have been high. So far, 105 influenza-associated deaths in children have been reported. 
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

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Interim Estimates of 2019–2020 Seasonal Influenza Vaccine Effectiveness 

Against Medically Attended Influenza from the US Flu VE Network

Brendan Flannery, PhD

Epidemiologist, Influenza Division

National Center for Immunization and Respiratory Diseases

Centers for Disease Control and Prevention

Dr. Flannery shared the following table to connect the genetic strains together with the names of 

the 2019-2020 Northern Hemisphere influenza vaccine components:

He presented data from the 5 US Flu VE Network sites with which CDC has cooperative 

agreements. The sites and Principal Investigators (PIs) are as follows:

 Baylor Scott and White Health (Manju Gaglani)

 Kaiser Permanente Washington (Mike Jackson & Lisa Jackson)

 Marshfield Clinic Research Institute (Ed Belongia & Huong McLean)

 University of Michigan (Arnold Monto & Emily Martin)

 University of Pittsburgh (Rick Zimmerman & Tricia Nowalk)

 

The methods are the same as have been used previously for the interim estimates. As a 

reminder, the case definition includes acute respiratory illness with a cough, so it is a more 

sensitive case definition for surveillance than the CDC ILI definition that includes fever. The 

clinics in these sites enroll outpatients >6 months of age with acute respiratory illness with 

cough ≤7 days duration. The data for this presentation included enrollment between October 23, 

2019 through January 25, 2020. The test-negative design used compares vaccination odds 

among influenza RT-PCR positive cases and RT-PCR negative controls. The vaccination status

for these interim reports is based on receipt of at least one dose of the current season’s 

vaccine. Vaccination status is determined based on a combination of medical records, 

immunization registries, and/or self-report. They do not have data on vaccine type-specific VE, 

but will have this at the end of the season when these documented records are all available. 

They can say that the vast majority of the vaccinated people in this dataset have received some 

type of injectable inactivated vaccine and not live attenuated influenza vaccine (LAIV). Fewer 

than 10 children in this dataset received LAIV, so there are no estimates for LAIV at this time. 

The adjusted estimates include study site, age, sex, self-rated general health status, 

race/Hispanic ethnicity, interval from onset to enrollment, and a 2-week interval for calendar 

time. 

There were 4112 participants enrolled from October 23, 2019 through January 25, 2020 at 52 

clinics at 5 sites. About 1060 (26%) tested influenza RT-PCR positive and about 3052 (74%) in 

the control group test influenza RT-PCR negative. The distribution, type, and subtype are shown 

in the following pie graph:

A(H1N1)pdm09 A/Brisbane/02/2018 (6B.1A)

A(H3N2) A/Kansas/14/2017 (3C.3a)

B Victoria B/Colorado/06/2017 (V1A.1)

B Yamagata B/Phuket/3073/2013 (Y3)
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

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A/H3N2

1%

A/H1N1pdm09

30%

A, unsubtyped

4% B/Yamagata

<1%

B/Victoria 

59%

Cases enrolled by (sub)type, 

N=1,060

H3N2 (11)

H1N1pdm09 (326)

A, unsubtyped (39)

B/Yamagata (3)

B, no 

As Ms. Brammer showed earlier, at the beginning of the seasons more B/Victoria was 

circulating than H1N1. Since that time, there has been more H1N1 than B/Victoria. Those 

continue to be the predominant influenza viruses circulating in the VE Network sties.

As a reminder, the enrolled participants are people presenting with acute respiratory illness 

(ARI) of all ages. Laboratory-confirmed influenza accounts for more than 40% of all ARI in these 

clinics during the peak of the season. They are maintaining about 40% positivity for enrollment 

currently.

In terms of the overall VE against any influenza, about 37% of the influenza positives were 

vaccinated and about 55% of the influenza negatives were vaccinated. The unadjusted estimate 

was 53%. After adjustment, the overall VE of this interim estimate is 45% with a confidence 

interval from 36% to 53%. Some age group difference is observed in VE. The estimate for those 

18 to 49 years of age is 25%. All 3 age-specific estimates are statistically significant.

The overall estimate for B/Victoria was 50%, the 6 months to 17 years of age estimate was 

56%, and the 18 years of age and older estimate has been combined because there were too 

few cases in the 50 year of age and older group to separate that out. There really is a shift in the 

age distribution of influenza B at the study sites toward the younger population. The estimate in 

those 18 years of age and older was somewhat lower at 32%, but was still statistically 

significant. In terms of some of the sequencing that has been done for viruses that are collected 

from the Flu VE Network. Out of the 670 influenza positives, 262 B/Victoria viruses have been 

sequenced. Among those, 256 (98%) V1A.3 (2020 S. Hemisphere vaccine component, which is 

not the genetic group V1A.1 in the current vaccine.

Regarding H1N1-specific VE, overall VE was 37% with confidence intervals from 19% to 52%. 

The age-specific estimates show a great deal of difference from two significant estimates of 

51% in the 6 month to 17 years group and 50% in the 50 and older group. However, VE was 5% 

and not significant for those 18 to 49 years of age. The data from sequencing is not very 

informative in that at this level, the sequencing identified 94 (100%) of the H1N1 viruses from 

the Flu VE Network as belonging to the vaccine genetic group 6B.1A. There has been some 

variety in the H1N1 viruses that are circulating. It is unknown whether that is related to the lower 

VE among those 18 to 49 years of age at this point.
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These data from the US were published the week before this meeting in the MMWR. In 

Eurosurveillance during the same week, CDC’s colleagues from Canada presented the VE 

estimates for the 2019-2020 seasons for Canada. The vast majority of their estimate for 

influenza B, which includes all influenza B, are B/Victoria. Canada’s estimates are slightly higher 

than the US estimate for influenza B, but are comparably reassuring in that the vaccine in 

Canada does seem to provide protection against the majority B/Victoria virus that is the triple 

deletion and not the virus that is in the Northern Hemisphere vaccine formulation. The second 

piece of data from Canada is that they did have enough H3N2 in their surveillance network to 

provide an All Ages and a 20-64 year old estimate. The main H3N2 virus, like in the US, is not 

the subclade or clade that is in the vaccine, the 3C.3a. As in the US, Canada is seeing a 

majority of 3C.2a1 virus. Again, this is evidence that vaccine is providing some protection 

despite circulation of virus that is actually different from the genetic group that is in the vaccine. 

The H1N1 estimates that differ in Canada from what is observed in the US Flu VE Network at 

this point is that their All Ages estimate is 44%, which is very similar to the US All Ages 

estimate. The estimate for 1 to 19 year olds 63% and for 20 to 64 year olds is 39%, which 

although slightly lower than in previous seasons in Canada in the 1 to 19 year olds is higher and 

statistically significant than what is seen in the US Flu VE Network [Skowronski et al, 

Eurosurveillance 21 Feb 2020. www.eurosurveillance.org].

The other thing to put this into context is the pyramid from the website that shows over the past 

10 years or since the pandemic, the number of deaths hospitalizations, and illnesses that occur 

in each influenza season. The higher limits are from the 2017-2018 season shown in the table 

on the right. The last season had 35 million estimated illnesses, almost half a million 

hospitalizations, and 34,000 deaths. The deaths, hospitalizations, and cases averted by 

vaccination last season were published in January 2020 by Chung et al in Clinical Infectious 

Diseases. End-of-season VE for the 2018-2019 season was around 26%. There was very low 

effectiveness against H3 that predominated for half of the season. Despite that disappointingly 

low effectiveness, the deaths, hospitalizations, and cases averted are still substantial. Estimates 

from the 2019-2020 season are expected sometime in Fall 2020.

In summary, the interim estimates from the 2019-2020 season indicate that vaccination reduced 

medically-attended illness due to any influenza virus type by 45% (CI: 36 to 53) based on 

enrollment through January 25, 2020. Encouraging signs are seen of VE of 55% against any 

influenza in children who have been hit particularly hard by influence this season. Vaccination 

provided 50% (CI: 39 to 59) protection against the predominant influenza B/Victoria virus (clade 

V1A.3). Overall effectiveness against H1N1pdm09 was 37% (CI: 19 to 52). As H1N1pdm09 

circulation has increased since January 2020, increased enrollment is expected to improve the 

precision of age-specific estimates later in the seasons.

Discussion Points

Regarding the test negative design, Dr. Lee asked whether the reason for the lower 

effectiveness rate in the 18 to 49 year olds had anything to do with household vaccination rates 

in terms of whether they know if these are parents of children who were vaccinated, which 

somehow may influence the estimates for that age group. In addition, she wondered whether 

infant deaths looked similar to prior years in which approximately 50% of the infants were 

completely healthy and whether there was any information about comorbidities.
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

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Dr. Flannery responded that the test negative design does not really account for indirect effects, 

and indirect effects are relatively hard to measure. It is a pretty good design for individual effects 

of the vaccine. The main reason for the test negative design is to control for differences in the 

population in health-seeking behavior among those who are vaccinated and those who are not 

vaccinated. If there is individual protection of influenza vaccine, it should be seen with this 

design even if there is a large indirect effect if that age group is having more exposure to young 

children or where the vaccine is less likely to work because they have some intense exposure. 

Just to put this in perspective for last year’s H1N1 estimates, good effectiveness was observed 

in that same age group. There was a change in the vaccine virus and in what was circulating, 

but there was effectiveness of H1N1 for last year’s vaccine at this time, which is not seen this 

year.

Ms. Brammer indicated that this year is similar in terms of infant deaths in that 53.5% of the 

infants had no previous medical conditions.

Dr. Bernstein asked whether there was an explanation for the fact that the B/Victoria strain in 

circulation is not matching the vaccine strain well, yet VE in children was 55% in the younger 

age group.

Dr. Flannery clarified that the point he did not make in the presentation was that the B/Victoria 

VE this season with the difference in the genetic group of what is circulating from what is in the 

vaccine is similar and in the same range of VE that has been seen against B/Victoria in seasons 

where it has been well-matched. It is difficult when it is said not to be matched, because that is 

usually based on antigenic differences. As Ms. Brammer showed, the antigenic differences are 

not so clear in the comparison. The majority of viruses that have been antigenically 

characterized, or 60%, still show as similar to the vaccine virus. There is obviously some crossreactivity, which is good news for children. It is somewhat surprising that the VE against 

B/Victoria is as high as it is in children with both the severity of the season and the vaccine 

being different from what is circulating. At this point, it is reassuring that the vaccine is providing 

protection. Low VE cannot be said to be contributing to the particularly bad season that is 

occurring, given that some protection is being seen.

Dr. Frey asked how many of the children who died were vaccinated.

Dr. Brammer indicated that among the children who died, the vaccination rate is very similar to

what has been seen in previous seasons in which only about 20% of the children are 

vaccinated. Through Week 7, with the limited information CDC has, it is 16.6% so far this year.

Safety of Adjuvanted vs. High-Dose Inactivated Influenza 

Vaccines in Older Adults: Preliminary Safety Results

Kenneth Schmader, MD

Duke University Medical Center

Dr. Schmader presented the preliminary results of the study of the safety of adjuvanted versus 

high-dose IIV in older adults. He noted that this work was supported by CDC through the 

Clinical Immunization Safety Assessment (CISA) Project in collaboration with Duke University 

Medical Center (Lead Site), Boston University Medical Center (Contributing Site), and Cincinnati 

Children’s Hospital Medical Center (Contributing Site, Boston University Sub-Contract). He also 

noted that the findings and conclusions in this presentation were those of the presenter and do 

not necessarily represent the official position of CDC.
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

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In terms of the rationale behind the study to prevent influenza in older persons, ACIP 

recommends vaccination with any US-licensed, age-appropriate influenza vaccine. The trivalent 

high-dose (HD-IIV3; Fluzone® High-Dose) and adjuvanted (aIIV3; FLUAD®) influenza vaccines 

are licensed for use only in persons aged 65 years and older in the US and may have improved 

effectiveness compared to standard dose (SD)-IIV3. Therefore, clinicians and patients have an 

important choice to make. Important factors in making that choice are safety and reactogenicity. 

However, the safety of HD-IIV3 and aIIV3 has not been compared directly head-to-head in the 

same clinical trial in the US. Furthermore, the relative impact of HD-IIV3 and aIIV3 reactions on 

health-related quality of life (HRQOL) has not been studied. That is a novel component of this 

study.

The first primary study objective was to compare the proportions of moderate-severe injectionsite pain after aIIV3 and HD-IIV3. This was selected as a primary objective because injectionsite pain likely would be causally related to the vaccine, and pain that is moderate (defined as 

some limitation in normal daily activities) or severe (defined as completely unable to perform 

normal daily activities) are obviously clinically meaningful. The hypothesis was that the 

proportion of subjects who have moderate-severe injection-site pain within the first week postvaccination will be non-inferior (not higher) for aIIV3 compared to HD-IIV3. The rationale for the 

non-inferior analysis lay in the fact that the adjuvanted vaccine was licensed in 2015 as the first 

adjuvanted influenza vaccine used in the US; whereas, HD-IIV3 was selected as a comparator 

because it had been licensed in the US since 2010 and at the time of the study was in wide use. 

There was substantive evidence supporting its safety. The co-primary study objective was to 

compare SAEs and adverse events of clinical interest (AECI) after aIIV3 and HD-IIV3 in the 

study population and by age-groups of 65-79 years and ≥80 years. Due to time limitations, Dr. 

Schmader presented on the results for the full study population, not the age group analysis. The 

secondary endpoints were to: 1) compare the proportions of local and systemic reactions (other 

than moderate-severe injection-site pain) after aIIV3 and HD-IIV3 in the full study population 

and by age group (65-79 years and ≥80 years); and 2) describe and compare change in 

HRQOL after aIIV3 and HD-IIV3 in the full study population and by age group.

In terms of the study design and participants, this was a randomized, blinded clinical trial of 

aIIV3 versus HD-IIV3 during the 2017-2018 and 2018-2019 influenza seasons. The sites were 

Duke University (2017-2019), Boston University (2017-2019), and Cincinnati Children’s Hospital 

Medical Center (2018-2019). The participants were community-dwelling volunteers aged ≥65 

years of age with the main eligibility criteria being not being immunosuppressed, being 

cognitively intact, having no co-vaccination, and having no influenza vaccine contraindications. 

The goal was to enroll ≥20% individuals aged ≥80 years. The participants were randomized 1:1 

to receive a 0.5 ml intramuscular (IM) dose of aIIV3 or HD-IIV3 and stratified by age group (65-

79) and (≥80) years. For the safety and reactogenicity assessments, participants were 

monitored in clinic ≥15 minutes post-vaccination for AEs, including syncope. Solicited 

reactogenicity events and unsolicited AEs were assessed using a standard symptom diary

starting at Day 1 (vaccination day) through Day 8. SAEs were assessed during Day 1 through 

Day 43 post-vaccination. AECIs included syncope during clinic post-vaccination monitoring, 

anaphylaxis in first 24 hours after vaccination, and Guillain-Barré syndrome (GBS) within 43 

days post-vaccination, and new onset immune-mediated conditions within 43 days postvaccination.
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

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For the HRQOL assessments for both seasons, the main measure was the EuroQOL-5 

dimensions-5 levels (EQ-5D-5L). This measures mobility, self-care, usual activities, 

pain/discomfort, and anxiety/depression rated on 5 levels: no problems, slight problems, 

moderate problems, severe problems, and extreme problems. Responses were converted to a 

utility index summary measure that ranges from -0.109 (worst health) to 1.000 (best health). The 

EuroQol-Visual Analogue Scale (EQ-VAS) also was used, which is a self-rated health measure 

in a thermometer format on a 0 to 100 scale with 100 being the best imaginable health stage 

and 0 being the worst in the participant’s estimate on that day.

The sample size estimate was 668 participants, with 334 per group. This assumed that 5% of 

older adults have moderate to severe injection-site pain after aIIV3 or HD-IIV3 based on 

prelicensure studies, a clinically meaningful non-inferiority margin of 5%, a one-sided alpha of 

0.025, and at least 80% power to demonstrate proportion of moderate-severe pain non-inferior 

after aIIV3 versus HD-IIV3. For the primary outcome of moderate to severe injection site pain, 

the investigators used a one-sided alpha of 0.025 level, an upper bound of a stratified by site 

Newcombe binomial confidence interval, and a non-inferiority margin of 5%. 

Regarding the results, a total of 778 participants were assessed for eligibility. Of those, 21 were 

excluded as 13 did not meet the eligibility requirements and 8 declined to participate. A total of 

757 were randomized. The Full Analysis Population 1 was comprised of individuals who were 

randomized, vaccinated, and had at least one day of symptom diary data. This population was 

used for SAEs, AECIs, and HRQOL analyses. The Full Analysis Population 2 were individuals 

who were randomized and vaccinated, and this was for injection site and all other reactions. 

There were 2 people missing symptom diary data in the HD-IIV3 group, so there were 377 in 

that group.

In terms of the summary of participants enrolled and randomized by site, it is important to note 

that 21.5% of the participants were ≥80 years of age. This met the goal of 20% or more. 

Regarding demographic characteristics, the median age was 72 years. The percentage of 

females was similar in both groups at 56% for allV3 and 54% for HD-IIV3. For reference, 

females represent 56% of the general US population over age 65 based on 2018 data. With 

respect to race, 76% to 80% of participants were white and 15% to 18% were Black. Again, for 

reference, in the general US population over 65 years of age, 77% are white and 13% are 

Black. The investigators measured 15 other chronic medical conditions (cardiovascular, 

respiratory, and others) in older adults and found them to be equally balanced between the two 

groups.

Regarding the primary outcome results for injection site pain, the majority of individuals in both 

groups reported no injection site pain. For moderate to severe pain, the allV3 group was 3.2% 

and the HD-IIV3 group was 5.8%. For the non-inferiority analysis, the percent difference was 

calculated for aIIV3 minus HD-IIV3, which was -2.7%. The upper limit of the 95% CI of the 

difference for aIIV3 minus HD-IIV3 was 0.36% and the noninferiority margin was 5%. The 

proportion of participants with moderate to severe injection-site pain after aIIV3 was non-inferior 

(not higher) than the proportion after HD-IIV3. For the co-primary objective, no SAEs were 

determined to be related to the vaccination. Also, there were no significant differences in the 

proportion of SAEs between the vaccine groups. There were 9 participants in the allV3 group 

who had ≥1 SAE after aIIV3 (2.4%; 95% CI:1.1, 4.5), and 3 participants had ≥1 SAE after HDIIV3 (0.8%; 95% CI 0.2, 2.2). No AECI occurred. 
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In terms of moderate to severe local reactions after aIIV3 and HD-IIV3, no local reactions led to 

a medical visit. Local reactions included injection site pain, redness, shoulder pain, swelling, and 

tenderness. The absolute differences were small between these groups. In fact, the largest 

difference was only 3.7% in swelling, which was higher in the HD-IIV3 group. Tenderness did 

not meet the non-inferiority criteria for aIIV3, while all of the other reactions did. None of these 

local reactions led to a medical visit. Regarding moderate to severe systemic reactions after the 

two vaccines, the reactions included chills, diarrhea, fever, headache, myalgia, nausea, 

vomiting, arthralgia, fatigue, and malaise. Again, the absolute differences were small between 

the groups. The largest difference was fatigue at 3.1%, which was higher in the adjuvanted 

group. Arthralgia, fatigue, and malaise did not meet non-inferiority criteria but the other reactions 

did. There were no systemic reactions that led to a medical visit.

Turning to the secondary objectives from Day 1 pre-vaccination to Day 1 post-vaccination, for 

the EQ-5D-5L. The difference of -0.05 (-0.06, -0.04) was the exact same between the two 

groups, with no significant difference. The scores increase slightly for the groups. Higher scores 

are better, but the differences are not clinically meaningful. For the EQ-VAS, the difference was 

-2.22 (-3.38, -1.06) in the aIIV3 group and 2.45 (-3.45, -1.54) in the HD-IIV3 group. Again, there 

was no significance between group differences. The scores increased again, which was not 

clinically meaningful. The pre-vaccination mean day scores for the EQ-5D-5L was 0.89 for the 

aIIV3 group and 0.90 for the HD-IIV3 group, meaning that this is a relatively healthy and 

independent group of elders.

In summary, the proportion of participants with moderate-severe injection-site pain was not 

higher after aIIV3 than HD-IIV3. There were no vaccine-related SAEs. The short-term postvaccination HRQOL was not affected by either vaccine. The safety findings in this study were 

consistent with pre-licensure data for aIIV3 and HD-IIV3. From the standpoint of safety, either 

vaccine is an acceptable option for the prevention of influenza in older adults. 

Discussion Points

Dr. Szliagyi inquired as to whether there was a reason for the fact that the population was quite 

healthy.

Dr. Schmader indicated that this is very typical in vaccine trials in older adults comprised of 

community-dwelling volunteers. People from nursing homes do not volunteer for these studies. 

It is possible to recruit them, but it is much more difficult. This is a recurring issue and 

represents a major gap in the literature not only for vaccines, but also for medications.

Dr. Talbot asked whether it was possible to assess immunogenicity and reactogenicity to 

determine whether there was a correlation.

Dr. Schmader responded that the immunogenicity studies are currently underway. All of the 

results are anticipated in a month or two, at which time they can perform that analysis. 
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

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Summary and WG Considerations

Lisa Grohskopf, MD, MPH

Influenza Division, CDC

National Center for Immunization and Respiratory Diseases

Centers for Disease Control and Prevention

Dr. Grohskopf thanked the WG members and CDC staff who contribute regularly to the calls 

every month, twice a month and often deliver extensive data and presentations to the WG. 

Before discussing the WG considerations over the last several months, Dr. Grohskopf shared a 

brief influenza vaccine distribution update. She shared the following data assembled by Dr. 

Santoli and her group in the Immunization Services Division (ISD). This is an update of a 

graphic presented during the October 2019 ACIP meeting summarizing vaccine dose 

distribution for the current season and the previous 3 seasons. This graphic depicts that 

approximately 174 million doses of influenza vaccine have been distributed in the US as of 

February 14, 2020:

As a reminder, these are the types of influenza vaccines:

IIV Inactivated Influenza Vaccine

ccIIV Cell Culture-Based Inactivated Influenza Vaccine

aIIV Adjuvanted Inactivated Influenza Vaccine

HD-IIV High-Dose Inactivated Influenza Vaccine

RIV Recombinant Influenza Vaccine

LAIV Live Attenuated Influenza Vaccine

Numbers indicate the number of influenza virus antigens:

 3 for trivalent: an A(H1N1), an A(H3N2), and one B (from one 

lineage)

 4 for quadrivalent: an A(H1N1), an A(H3N2), and two Bs (one 

from each lineage)
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A discussion was presented during the October 2019 meeting of the rationale and design for a 

systematic review of influenza vaccines in older adults that have been discussed in the WG for 

a number of calls. Older adults ≥65 years of age are recognized as a group that is at increased 

risk for severe illness and complications due to influenza infection. They also are a group who 

tend not to have as good results in terms of efficacy or effectiveness with vaccines as compared 

to younger, healthier age groups. They also are the group age-wise who have the most in terms 

of number of influenza vaccines that suitable for them purely based on age indications. Since 

2013-2014, there has been a decent expansion of the number of different types of vaccines 

available, which are shown in the following table:

This includes 2 vaccines that are licensed specifically for adults 65 years of age and older, 

which is the adjuvanted aIIV3 and HD-IIV3. The aIIV3 has MF59® adjuvant the HD-IIV3 has a 

higher antigen dose of the hemagglutinin and antigen. Both are licensed for this age group in 

order to encourage a stronger immune response and better effectiveness or efficacy. Both 

adjuvanted and high-dose inactivated vaccines have been studied as compared to 

unadjuvanted standard-dose inactivated vaccines in this population. For each vaccine, there is 

some evidence of better efficacy in this age group depending upon the study. There also has 

been at least one study of RIV, which was first licensed in 2013-2014 as a trivalent and then

became available as a quadrivalent in the 2017-2018 season. This is licensed for individuals 18 

years of age and older, but has been specifically studied in adults 50 years of age and older in 

an RCT compared to a quadrivalent inactivated vaccine. Out of a total of the 9 US licensed 

influenza vaccines available for 2019-2020, 8 of which are appropriate by age indication. ACIP 

recommends that a licensed, age-appropriate influenza vaccine should be used. No preferential 

recommendations are made for any specific influenza vaccine for any age group, where there is 

more than one that is appropriate. This is the case for many age groups, but particularly for 

individuals 65 years of age and older.

As alluded to in Dr. Schmader’s presentation, providers and the public do ask questions about 

whether one vaccine is more appropriate for any given person. During the October 2019 ACIP 

meeting, the WG discussed the status of the development of a protocol for a systematic review 

of influenza vaccines. The systematic review/meta-analysis question regards “whether the 

relative benefits and harms of HD-IIV, aIIV, and RIV, as compared with one another and with 

other influenza vaccines, favor the use of any one or more of these vaccines over other age-
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appropriate influenza vaccines for persons ≥65 years of age.” This is a relatively complicated 

question given the number of vaccine comparisons embedded in there.

The PICO essentially has not changed since the WG first presented this. The population is 

adults ≥65 years of age. The interventions include US-licensed, or similar in 

formulation/manufacture to US-licensed, trivalent/quadrivalent high-dose IIV, adjuvanted IIV, or 

RIV. The comparators include other trivalent or quadrivalent influenza vaccine (US-licensed, or 

similar in formulation/manufacture to US-licensed), non-influenza control vaccine, placebo, and 

no vaccine. 

Outcomes have had an update since the last prestation, at which time the efficacy/effectiveness 

outcomes had been settled. Safety outcomes are somewhat more complicated and required 

further discussion. Much of the discussion centered around lumping versus splitting. There are 

many ways to enumerate safety events. A total of 8 primary outcomes were settled upon for 

efficacy/effectiveness and safety, which are as follows:

 Efficacy/Effectiveness

 All influenza A and B

 Influenza-associated outpatient/emergency visits

 Influenza-associated hospitalizations

 Influenza-associated deaths

 Safety

 Any systemic adverse event (Grade ≥3)

 Any injection site adverse event (Grade ≥3)

 Any serious adverse event (SAE)

 Guillain-Barre syndrome

There also are some secondary outcomes. To the extent data are available, the following will be 

summarized:

 Influenza-associated outpatient/emergency visits, hospitalizations, and deaths stratified by 

influenza virus type/subtype

 SAEs judged to be related to study intervention

Inclusion/Exclusion criteria are similar to what was presented in October 2019 and include the 

following:

 Peer-reviewed literature with no language restriction

 Publication dates from 1990 forward, with a rationale that the adjuvanted vaccine was 

licensed in Europe in 1997

 Main inclusion criteria: 

 Randomized studies (individually- and cluster-randomized designs) 

 Retrospective case-control and cohort studies (traditional and test-negative designs)

 Retrospective and prospective cohort studies
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 Main exclusion criteria: 

 Data involving influenza vaccines not licensed in the US for persons ≥65 years of age

 Studies/data for which the entire population falls outside the age range of interest

 Studies/data assessing monovalent or bivalent vaccines

 Case series, case reports, registry reports without comparator or denominator 

information

 Animal studies

 Interim reports superseded by final reports

The outcomes were finalized in November 2019, the protocol was finalized in December 2019, 

and literature screening began in January 2020. There are a substantial number of reports to 

screen at upwards of 8000. The WG will present the findings as soon as they are able.

Discussion Points

Dr. Lee thought it seemed like they might be headed toward a question about a preferential 

recommendation, which raised a couple of issues. One issue pertains to what would constitute a 

meaningful difference, and she wondered whether the WG would opine that to say what that 

difference may or may not be. It may not be statistically significant, but it may be clinically 

meaningful. The second issue pertains to determining comparative effectiveness conditioned on 

the same season, because her assumption is that there will be considerable data of several 

seasons that the comparison will be very challenging for different vaccines.

Dr. Grohskopf replied that they did not define a meaningful difference in the protocol, partly 

because everyone is aware of the variability of the way influenza behaves and the way VE differ 

from season-to-season. In terms of what they have seen, even relative VE is not the same from 

study-to-study. It is daunting to try to define a clinically meaningful difference when there are so 

many things going into the equation that cause variability. They anticipate seeing a lot of 

variability. Based on the WG discussions, the general feeling among the WG members about 

the reason for doing this is that people do ask why there is not a preferential recommendation. 

Given all of the evolving literature, it is a good time to examine whether there are enough data 

and if not, why not or if so, why so. There is going to be a lot of variability, but they will have to 

determine how much.

Dr. Foster (APHA) inquired as to why FLUCELVAX®, the cellular cultured vaccine, was not 

included in this evaluation.

Dr. Grohskopf indicated that the cell-based inclusion was discussed. One reason was that to the 

WG’s acquaintance, more data were available for the other 3 vaccines for this particular age 

group specifically. The review is quite complicated already with the 3 vaccines. To add the 4th

would broaden the review quite a bit more in terms of relative comparisons. Because the cellbased vaccine is licensed for individuals 4 years of age and older, the WG’s feeling was that this 

is likely to be addressed in a broader review in terms of egg-based versus non-egg-based for a 

broader scope of the population. The cell-based vaccine has been available for a number of 

seasons. In terms of manufacturing, the propagation of those reference strains has been since 

that vaccine was licensed in canine kidney cell lines rather than eggs. This is the first season in 

which all 4 of the reference strains are cell-derived. Therefore, it seemed best to hold off on 

FLUCELVAX® for a later review.
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Centers for Disease Control and Prevention (CDC)

Dr. Wharton presented the CDC agency update. During the December 2019 meeting of the 

Board of Scientific Counselors, Deputy Director for Infectious Diseases (BSC, DDID) 

established the Vaccine Confidence Work Group to identify gaps in CDC activities to increase 

vaccine coverage; inform the centers’ efforts to provide recommendations to CDC on the 

agency’s strategy to strengthen vaccine confidence; and maintain high vaccine coverage at the 

national, state, tribal, and local levels. Over the next two years, the Vaccine Confidence Work 

Group will collect and analyze relevant information and provide findings and observations to the 

BSC DDID for deliberation and potential votes. The Vaccine Confidence Work Group will be 

chaired by external experts; and will be supported by staff from across CDC, including the 

Immunization Services Division (ISD), the Immunization Safety Office (ISO), and the Division of 

Viral Diseases (DVD).

For measles during 2019, a total of 1282 individual cases were confirmed in 31 states. In 

October 2019, New York State (NYS) announced the end of the state’s nearly year-long 

outbreak of measles. With that declaration, the US was able to maintain its measles elimination 

status. The Pan American Health Organization has established a regional verification 

Commission and CDC will provide evidence regarding the sustainability of measles elimination. 

In December 2019, American Samoa declared a measles outbreak. CDC has provided technical 

guidance on case and contact investigations, infection control, vaccine acquisition and usage, 

and mass vaccination efforts. The agency also provided American Samoa with additional 

funding to support their response to the outbreak and purchase additional doses of measles, 

mumps, and rubella (MMR) vaccine.

The previous day, a comprehensive update was provided on the influenza vaccine season. Dr. 

Wharton added a couple of brief updates that she did not believe were included. CDC tracks 

influenza coverage weekly through the National Immunization Survey and is able to provide 

estimates that are updated weekly. She was pleased to see this year that coverage appears to 

be tracking a little above last year. It is currently around 60%. If it continues to increase, 

coverage will likely be higher than it was at the end-of-season last year. CDC is also pleased to 

see an increase in doses of pediatric influenza vaccine ordered by states for use in the 

Vaccines for Children (VFC) Program. Obviously, vaccine availability does not necessarily mean 

there will be higher coverage, but there cannot be higher coverage if there are not more dosage 

available. Therefore, CDC is pleased to see that increase in doses ordered for next season for 

the VFC Program.

Finally, the 2020 National Adult and Influenza Immunization Summit (NAIIS) annual in-person 

meeting will be convened on May 18-20, 2020 at the Westin Peachtree Plaza Hotel in Atlanta, 

Georgia to be followed by CDC’s National Immunization Conference (NIC), which will be 

convened May 19-21, 2020 also at the Westin Peachtree Plaza Hotel in Atlanta, Georgia. 

Information about both of those meetings is available online.

Agency Updates
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Department of Defense (DoD)

Dr. Deussing conveyed the DoD’s appreciation to ACIP and CDC for continued inclusion of the 

DoD in this meeting and the ACIP working groups. The DoD is closing out its 2019-2020 

influenza vaccination campaign after reaching its annual goal of vaccinating over 90% of 

personnel by January 15, 2020. This included Active Duty, Select Reserve Forces, and 

healthcare providers. New for the 2020-2021 season, the DoD will introduce Southern 

Hemisphere influenza vaccine to support operational activities in applicable regions. The DoD, 

in coordination with other agencies, is moving forward with limited implementation of the newly 

licensed Bavarian Nordic smallpox and monkeypox vaccine. The Immunization Healthcare 

Division (IHD) is developing a protocol to evaluate this vaccine for cardiac safety, interaction 

with other vaccines, and optimum booster interval. The Pragmatic Assessment of Influenza 

Vaccine Effectiveness in the DoD (PAIVED) is now in its second research year. Over 5800 

patients were enrolled this year at 9 different research sites. This study group is co-chaired by 

the IHD and the Uniformed Services University (USU) Infectious Disease Clinical Research 

Program (IDCRP). The South Atlantic and Pacific Regional Vaccine Safety Hubs continue to 

actively present research on a number of subjects, including atypical shoulder pain and 

dysfunction following immunization, vaccine hesitancy in the military system, and effects of antiinflammatories and analgesics post-immunization. In FY2019, the IHD responded to over 1400 

calls to its call center, reviewed 1022 VAERS cases, reviewed 480 clinical cases, and 

conducted 322 onsite quality assurance surveys to ensure the highest standards of care 

throughout the DoD. 

Department of Veterans Affairs (DVA)

Dr. Kim provided 4 announcements for the DVA. The first is that the VA updated its clinical 

preventive services guidance and national electronic decision support tools, which are also 

known as clinical reminders, for HPV and pneumococcal immunizations based on the most 

recent ACIP recommendations. Located on the VA internal website for clinicians, the VA 

guidance also includes public facing links and resources for staff to use with their patients. 

Second, from August 1, 2019 through February 1, 2020, over 1.9 million influenza vaccinations 

were administered within VA facilities. This does not include vaccines received outside of the 

VA. In addition, more than 109,000 enrolled veterans received a no-cost influenza vaccine 

through a partnership with Walgreen’s. Third, VA Notice 2020-02 was released to the field on 

the storage of vaccines and medications in pharmaceutical grade purpose-built refrigerators and 

freezers at VA medical facilities. Fourth, the VA public facing “Staying Healthy: 

Recommendations for WOMEN" and “Staying Healthy: Recommendations for MEN” have been 

updated based on the CDC 2020 Adult Immunization Schedule and are available on the VA 

National Center for Health Promotion and Disease Prevention website. 

Food and Drug Administration (FDA)

Dr. Fink indicated that first and foremost, FDA is engaging with vaccine manufacturers, other 

federal agencies, and regulatory and public health authorities across the world to facilitate 

development of vaccine candidates to address the current COVID-19 outbreak. Since the last 

ACIP meeting, there have been 4 major vaccine approvals. ERVEBO, the VSV-vectored Ebola 

vaccine, was approved in December 2019. There have been 3 influenza vaccine approvals, two 

of which were to add quadrivalent formulations to previously approve trivalent seasonal 

influenza vaccines. This includes a quadrivalent formulation of Fluzone® High-Dose indicated for 

use in individuals 65 years of age and older that was approved in November 2019; and a 

quadrivalent formulation of Fluad®-MF59®-adjuvanted influenza vaccine that was approved at 
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

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the end of January 2020, also for use in individuals 65 years of age and older. The fourth 

approval was for an adjuvanted H5N1 vaccine for positioning in the Strategic National Stockpile 

(SNS). This is an MF59®-adjuvanted vaccine that is manufactured using the same platform as 

FLUCELVAX®, the licensed seasonal influenza vaccine. The trade name is AUDENZ. This 

vaccine was studied for safety in nearly 4000 individuals, which included over 300 pediatric 

subjects and nearly 1800 individuals 65 years of age and older. The effectiveness was inferred 

by hemagglutinin inhibiting antibody responses post-vaccination and from efficacy data with 

FLUCELVAX®, the vaccine manufactured using the same platform. This H5N1 vaccine was 

approved under FDA’s traditional approval pathway for adults 18 years of age and older 

because FLUCELVAX® is approved under that pathway as well. For pediatric individuals under 

the age of 18 years, FLUCELVAX® is approved under either an accelerated approval provision 

or not yet approved, as is the case for individuals less than 4 years of age. Once the ongoing 

studies to support traditional approval of FLUCELVAX® are completed, that will serve as the 

basis for full approval of AUDENZ in those pediatric age groups.

Health Resources and Services Administration (HRSA)

In terms of Ebola vaccine coverage by the Countermeasures Injury Compensation Program 

(CICP), Dr. Rubin reported that Ebola vaccine is a covered countermeasure based on the 

current declaration. Injury claims from the Ebola vaccine are eligible for benefits as long as they 

meet program requirements. As of January 1, 2020, the CICP has compensated 39 claims 

totaling $5.5 million. The national Vaccine Injury Compensation Program (VICP) has continued 

to process an increased number of claims. In Fiscal Year 2019 (FY2019), 1282 claims were 

filed with the VICP. In that same FY, $196.2 million was awarded to petitioners and $29.2 million 

was awarded in attorney fees and costs. These include fees for compensated, dismissed, and 

interim cases. As of January 1, 2020, a total of 289 claims were filed with the program and 

$57.2 million was awarded to petitioners and attorneys for attorney fees and costs. As of 

January 1, 2020, HRSA has a backlog of 913 claims alleging vaccine injury awaiting review. 

More data about the program can be obtained on the website.

Indian Health Service (IHS)

Dr. Weiser reported as of February 10, 2020, IHS has administered 267,565 doses of influenza 

vaccine with population coverage among children 6 months to 17 years of age of about 36.1% 

and among adults 18 years of age and older, 33.6%. In addition, IHS facilities have a mandatory 

HCP influenza policies. Internal influenza vaccine coverage among federal IHS HPC was 94.8% 

as of December 31, 2019. One of the software updates that IHS is grateful to be anticipating will 

be established soon is the final phase of new immunization forecasting software, which finally 

will allow IHS to catch up with some of its newer vaccine recommendations. This is expected to 

go live in the next 30 to 60 days. Addressing vaccine hesitancy, the Northwest Portland Area 

Indian Health Board (NPAIHB) Tribal Epidemiology Center (TEC) with funding from CDC is 

working with various stakeholders, parents, community members, HCP, and a community 

organization called Boost Oregon to develop approaches and communication strategies to 

strengthen conversations among HCP and community members around the importance and 

benefits of childhood vaccines and to reduce vaccine hesitancy within tribal communities. The 

projects aims are to: 1) educate patients and parents about childhood vaccines; 2) increase 

HCP’s confidence and ability to discuss patient and parent concerns about vaccines; and 3) 

encourage providers to strongly recommend immunizing all children according to the ACIP 

published vaccination schedules for children and adolescents. 
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National Institutes of Health (NIH)

Dr. Mulach reported National Institute of Allergy and Infectious Diseases (NIAID) is supporting 

the development of a number of COVID-19 vaccine candidates by intramural and extramural 

investigators. Multiple approaches are being assessed, including vaccines based on 

technologies that have shown promise against coronaviruses that cause SARS and MERS. The 

Vaccine Research Center (VRC) at NIAID is collaborating with the company Moderna on the 

development of a vaccine candidate using a messenger ribonucleic acid (mRNA) vaccine 

platform expressing a recombinant spike protein of SARS-CoV-2. It is anticipated that this 

experimental vaccine will be ready for clinical testing in the next few months. NIH will continue 

to conduct pre-clinical studies as well as the first in-human study of this candidate and other 

candidates. NIH is coordinating closely with its colleagues at CDC, the Department of Health 

and Human Services (HHS), FDA, DoD, and other federal partners.

On February 26, 2020, NIH announced the start of a randomized controlled clinical trial to 

evaluate the safety and efficacy of the investigational antiviral remdesivir in hospitalized adults 

diagnosed with coronavirus disease 2019 at the University of Nebraska Medical Center (UNMC) 

in Omaha. This is the first clinical trial in the US to evaluate an experimental treatment for 

COVID-19. The first trial participant is an American who was repatriated after being quarantined 

on the Diamond Princess Cruise Ship that docked in Yokohama, Japan and volunteered to 

participate in the study. The study can be adapted to evaluate additional investigative 

treatments and to enroll participants in other sites in the US and worldwide.

As Dr. Messonnier mentioned the previous day, CDC received a clinical specimen of the first 

US patient infected with SARS-CoV-2, prepared the sample, and sent it to the NIH BEI 

Repository. That sample has been grown up and is available to investigators to use in their 

research endeavors for those who are registered. NIH is providing additional materials for 

coronavirus research, which are being updated on a daily basis as more information is acquired. 

The BEI Repository website contains further information about those resources. 

Office of Infectious Disease Policy and HIV/AIDS (OIDP)

Dr. Elam, Research & Policy Strategist for OIDP, provided a brief update on OIPD 

immunization-related activities and the National Vaccine Advisory Committee (NVAC). The last 

NVAC meeting occurred February 13-14, 2020 and focused on vaccine confidence and 

innovation. The agenda included presentations on recent research in vaccine innovation, 

updates related to the coronavirus outbreak, and efforts to advance the 2019 Executive Order 

on Modernizing Influenza Vaccines in the United States to Promote National Security and Public 

Health. The agenda also included sessions on challenges and opportunities for combatting 

misinformation online, speakers from large social media companies such as Twitter, and the 

use of storytelling to increase vaccination awareness and rates. The Assistant Secretary for 

Health (ASH) in a prior meeting charged NVAC to develop and formally submit reports with 

implementable recommendations for vaccine confidence and immunization equity. During the 

meeting, each of the subcommittees provided an update on their progress in preparations for 

drafting and submitting these reports on time. The next public NVAC meeting will take place 

June 9-10, 2020 in Washington, District of Columbia (DC). For those who cannot attend in 

person, there will be a live webcast. Information for this upcoming meeting and past meetings 

can be found on OIDP’s website.
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OIDP will be releasing the 2020 National Vaccine Plan (NVP) late this year. During the last 

ACIP meeting, Dr. Tammy Beckham, OIDP’s Director, updated this committee on the progress 

related to the development of the 2020 NVP. The work on this plan is ongoing and includes 

review and incorporation of feedback solicited through public comment and stakeholder 

discussions that took place in October 2019. This consisted of 26 one-hour discussions with 

individuals and a variety of stakeholder groups including healthcare providers, industry, 

academia, and patient advisory organizations. Much of the feedback received aligned closely 

with previous NVAC recommendations including aspects such as a goal for innovation, and a 

global goal relevant to the ongoing coronavirus outbreak. At present, OIDP is integrating the 

feedback received into a concise actionable 5-year plan that will provide vaccine strategies 

across the life course, guide priority actions for 2020-2025, and identify indicators to measure 

progress toward planned goals.

As will be emphasized in the next NVP, vaccine innovation continues to be a priority at HHS as 

they recognize the critical role of innovation within the US vaccine and immunization enterprise. 

OIDP is putting innovation into practice in multiple ways. For example, in order to improve 

pertussis vaccine performance, OIDP convenes scientific, policy, and regulatory experts to 

discuss ethics, feasibility, and regulatory considerations of a controlled human challenge model. 

This human challenge model will provide a better understanding of the immune system’s 

response to infection, including colonization, and guide pertussis vaccine development in the 

US. As opposed to current practice, the challenge model will entail colonization as the desired 

endpoint. The output of this meeting was instructive and will serve to guide future policy. A 

White Paper will be published in Spring 2020.

Human papillomavirus (HPV) remains a significant public health challenge, with vaccination 

completion rates for adolescents barely above 50%. The ASH has prioritized increasing HPV 

vaccination rates nationally in order to reduce vaccine-preventable cancers. As a result, OIDP is 

implementing innovative approaches to significantly improve HPV vaccination rates within the 

next 5 years. This is being achieved through a number of activities, including working with the 

CDC, the American Medical Group Association (AMGA), and the American Cancer Society’s 

(ACS’s) National HPV Vaccination Roundtable to establish a Learning Collaborative among 

integrated delivery networks and other large health systems. Additionally, OIDP has launched 

the innovative Million Cancer Preventing Congregations program, a faith-based initiative that 

empowers leaders to participate in prioritizing HPV vaccination and cancer prevention within 

their congregations.

In addition, Dr. Elam provided an update on two national plans that will be released later in 

2020. First, OIDP is updating the National Viral Hepatitis Action Plan, which was first released in 

2011. This plan provides goals, strategies, and indicators to achieve a coordinated national 

response to Hepatitis A, B, and C infections. The updated plan is scheduled to be released in 

Summer 2020 and will prioritize available hepatitis vaccinations. OIDP is also advancing the first 

ever STI Federal Action Plan. Recent data show that rates of STIs have grown considerably 

over the past 5 years and had reached an all-time high in 2018. Acknowledging this serious 

public health concern, HHS is developing the STI Federal Action Plan to guide a strategic 

federal response. This plan will focus on the 4 most common STIs that have the greatest public 

health impact in the US: chlamydia, gonorrhea, syphilis, and HPV. HPV vaccination will be 

emphasized as a cancer-preventing measure. The plan will focus on cross-cutting issues, 

including stigma, disparities, and social inequities.
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Introduction

Sharon Frey, MD, FACP, FIDSA

Saint Louis University School of Medicine

Chair, ACIP Human Rabies Prevention WG

Dr. Frey introduced the Human Rabies Prevention WG members and session. The WG’s terms 

of reference are to:

 Determine the epidemiology and burden of rabies exposures and pre-exposure prophylaxis 

(PrEP) and post-exposure prophylaxis (PEP) administration in the US

 Evaluate and revise recommendations as needed for vaccination schedules, route and site 

of PrEP and PEP, and cost-effectiveness

 Consider evidence generated to inform the rabies recommendations of other global 

organizations, such as the World Health Organization (WHO) 

 Review rabies exposure risk and risk assessment guidelines for the general population and 

by occupational and recreational groups

 Evaluate serological and monitoring recommendations, including whether recommendations 

should differ depending on the degree of rabies risk for a person and whether adequate 

antibody titers are needed to confirm immunization

 Consider whether recommendations should differ for healthy adults compared to 

immunocompromised persons, children, and pregnant women

 Update recommendations with information about the 2 rabies immune globulin products 

approved by the US FDA during 2018

 Identify areas in need of further research for informing future vaccine and immune globulin 

recommendations

To recap the October 2020 meeting, the following information was presented and discussed:

 Background: epidemiology, clinical course, and rabies biologics in the US

 Factors that contribute to decisions for PrEP and PEP

 The role of neutralizing antibodies as a marker for adequate vaccine response

 Introduction to PrEP schedule considerations, including:

 Immunogenicity and duration of immunity

 Route of vaccine administration

 Role of booster doses for select populations

 Reasons for PrEP failures

 

Rabies Vaccine
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Since the last ACIP meeting, the WG concluded data review and discussions about PrEP topics 

and began discussing PEP to include PEP schedules, data about rabies immune globulin (RIG) 

administration, and presentations about newly licensed RIG products. Presentations during this 

session included the following:

 Background to PrEP, vaccine safety, and WG considerations

 Rabies vaccine schedule and duration of immunity (systematic review data)

 Other guidance and next steps for the WG

Regarding the new tentative timeline, the WG hopes to provide PrEP GRADE and EtR and 

some PEP data in June 2020. In October, the WG anticipates having a PrEP vote and to 

continue presentations about PEP data, including GRADE and EtR. A vote is anticipated on 

PEP in February 2021.

Background to Rabies Pre-exposure Prophylaxis, 

Vaccine Safety, and Work Group Considerations

Agam Rao, MD FIDSA

CDR, United States Public Health Service

National Center for Emerging and Zoonotic Infectious Diseases

Centers for Disease Control and Prevention

Dr. Rao explained that rabies is an acute, progressive encephalomyelitis that is nearly always 

fatal. It is transmitted from infected mammals by a bite, scratch, or exposure to saliva or neural 

tissue. It is not transmitted by exposures to blood, urine, or feces of infected animals. There 

have been no known laboratory-confirmed cases of human-to-human transmission through 

exposure to infected persons. In the US, there are approximately 0 to 4 cases per year. Human 

cases mostly come from infected animals.

There are few animal species that are reservoirs for rabies. Rabies virus variants (RVV) are 

named for animal reservoir species in which they circulate. They are confined to geographically 

definable regions. Infection can be transmitted from the reservoir species to other species, for 

example, a racoon RVV can spread from a racoon to a cat to a human. It is important to 

understand that the RVV does not denote the animal to which the human was exposed. Within 

the US, canine RVV has been successfully eliminated. This leaves terrestrial or wildlife rabies 

and non-terrestrial rabies. Non-terrestrial rabies is rabies where the reservoir is bats. Bat RVV is 

widespread and is present in 49 of 50 US states—all but Hawaii. Terrestrial or wildlife rabies is 

rabies for which the reservoir is wildlife (e.g., skunk, fox, mongoose, and raccoon). Depicted in 

this map is the distribution of terrestrial RVV in the US: 
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Activities that have led to confirmed cases in the US are ones that bring humans closer to rabid 

animals or rabies virus. They occur in domestic and international settings. In both of those 

settings, recreational and occupational work like laboratory and field work have been involved.

Domestically, there are other potential exposures including contacts in everyday life, which 

occurs if there are bats in the home or a residence is in a wooded area with opportunities for 

exposure to rabid animals. There have been rare transmissions from organ and tissue 

transplants as well. 

For these reasons, preventing rabies is a priority. Vaccinating domestic and wild animals is one 

way of doing that. For example, USDA, health departments, and others work on oral rabies 

vaccine campaigns for this purpose. Vaccinations in humans, PrEP and PEP, have been found 

to be highly effective in preventing rabies and likely contribute to the low number of cases in the 

US. PrEP was the focus of this session. It is comprised of a rabies vaccine schedule. Over 

15,000 persons receive PrEP annually in the US.

In terms of US rabies vaccine, PrEP and PEP are important. A lot of factors contribute to the 

ACIP recommendations for these. There are 2 rabies vaccines currently licensed in the US.

There is a human diploid cell vaccine (HDCV) and purified chick embryo cell vaccine (PCECV). 

The brand name and manufacturer are listed in the second and third columns in the following 

table:

Vaccine Product 

Name

Manufacturer Licensed for 

Administration

Human diploid cell 

vaccine 

(HDCV)

Imovax® Sanofi Pasteur Intramuscularly

Purified chick embryo 

cell vaccine (PCECV)

RabAvert GlaxoSmithKline 

(In future: 

Bavarian Nordic)

Intramuscularly

Both vaccines are licensed in the US for intramuscular (IM) administration only. Both vaccines 

have been around for decades and no concerns were raised during the 2008 ACIP 

recommendations. However, because these vaccines are an important part of PrEP and PEP 

regimens, the WG did review the available data. The WG looked at passively collected data 

from the Vaccine Adverse Event Reporting System (VAERS). In terms of data for HDCV, 

VAERS received 1666 reports during 1990-2019. The take-home point is that the majority (94%)

of reports were for non-serious events. Systemic reactions observed included headache 

(18.8%), pyrexia (18.1%), and nausea (17.1%). Serious adverse events (SAEs) like 

angioedema were rarely reported. These findings are consistent with pre-licensure and postmarketing studies [Moro PL, et al PLoS Negl Trop Dis. 2016 Jul 13;10(7):e0004846 ; VAERS: 

Vaccine Adverse Event Reporting System].

For PCECV, VAERS received 739 reports. Here as well, most (93%) were non-serious. The 

most common systemic reactions observed were headache (19.5%), pyrexia (18.5%), and 

nausea (18.1%). These findings are also consistent with findings of pre-licensure studies and do 

not represent new information [Moro PL et al. Travel Med Infect Dis. 2019 May - Jun;29:80-81; 

Dobardzic A et al. Vaccine. 2007;25:4244–51; VAERS: Vaccine Adverse Event Reporting 

System].
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To ensure that any published data about safety since the 2008 ACIP recommendations were 

evaluated, the literature for trials was reviewed. Safety data from 25 trials were found to have 

been published since the 2008 ACIP recommendations. These publications involved

comparison of a new vaccine and one of the 2 US vaccines, intradermal administration, and 

intramuscular co-administration with other vaccines (e.g., Japanese Encephalitis vaccine), 

varying schedules, and use in pregnant persons and children. In the end, the findings were 

consistent with what has been previously reported and no change was found in the safety 

profile.

In terms of who should receive rabies PrEP, the purpose of PrEP is to provide partial immunity 

to persons who are at risk for rabies. It is not a substitute for PEP. Persons who receive PrEP 

still need PEP after an exposure. Rabies immune globulin would not be needed for these 

people, and the vaccine series would be shorter. However, receiving PrEP does not negate the 

need for PEP. It is intended for persons who may have unrecognized or frequent exposures to 

rabies virus. For persons who have a delay in starting PEP (for example, if they are in a rural 

area and have to travel to the capital city of an international country), PrEP provides a bridge 

until they have access to PEP. The recommendations for PrEP vary depending upon the level of 

risk to unrecognized exposures. Risk categories for PrEP were developed with this in mind.

They were developed to outline the populations who should receive PrEP based on a shared 

risk level and the corresponding recommendations for schedules and frequency of titer checks

that are specific for that level of risk. They are named for the level of risk for unrecognized 

exposures where “Continuous” is the highest risk, followed by “Frequent” and “Infrequent,” and 

finally “Rare” which is the least risk. The “Rare” category is the general population.

Dr. Rao walked through the important features of this table from the 2008 ACIP rabies 

recommendations, as all of the presentations during this session were based on understanding 

this table: 
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Focusing on the left side of the table, the first column is the risk category. Starting at the bottom 

is the “Rare” risk. There is increasing risk for inapparent or unrecognized exposures moving 

upward on the table to the “Continuous” category. The second column, “Nature of Risk” 

describes features of each risk category. For example, the nature of risk to unrecognized 

exposures is the highest for the “Continuous” risk category. Persons who fall into this risk are 

exposed to rabies virus in high concentrations and frequently. They can be exposed from bites, 

non-bites, or aerosol/droplet exposure. The nature of this risk decreases in intensity moving 

down the second column. For the general population, in the “Rare” category, exposure is always 

episodic if it occurs and the source is recognized. The recommended schedule and the 

frequency of titer checks differs depending on the risk category. The information in the third 

column, the “Typical Populations” column, is for that reason critical to front line providers. It 

enables them to identify the category in which their patient falls so that they can follow across 

and determine the PrEP recommendations. The populations described in the third column 

depend on several factors, including activity performed by the population, geographic region of 

mammal that someone might be exposed to, and access to safe and effective PEP. Dr. Rao 

spoke about each of these in more detail.

“Activity Performed” can mean occupational and recreational activities. Occupational exposures 

include jobs that require handling live rabies virus in diagnostic, research, or vaccine production 

capacities. For example, a rabies diagnostician. Some occupations have a lot of contact with 

bats, and some with terrestrial mammals. As part of recreation, too, some people have 

exposures that are risky for rabies. People can have contact with bats if they are a spelunker. 

People also travel internationally and can have exposures to rabid animals. Geographic region 

is important because different regions have different risks, regardless of the occupational or 

recreational activity that a person is doing. For example, domestically, a wildlife worker in 

Washington State where no terrestrial RVV are noted may have a lower risk than the same work 

in Pennsylvania, which is deep in the green zone where raccoon RVV is. Similarly, a spelunker 

entering only caves in Hawaii, where there is no rabies at all, may have a lower risk than a 

spelunker who enters caves in Alabama where there is bat RVV. Internationally, the important 

surveillance information is knowing whether canine RVV is an issue.

Geographic location is not the only important consideration for travelers. Access to PEP is a 

very important issue as well. Nearly all major cities have rabies vaccine and rabies immune 

globulin available. But if a person is, for example, doing recreational activities in a rural area, 

they may not have quick and easy access to the PEP that is in the major city. There may be a 

delay in their receiving PEP in that case. These 3 things fill in the “Typical Populations” column

of the table titled “Rabies pre-exposure prophylaxis guide” from the 2008 ACIP 

recommendations. However, over the years, CDC has heard that this column can be hard to 

follow.

To the left of the “Typical Populations” column is the corresponding risk category. Some of the 

reasons this column was confusing is that veterinarians are listed in 2 risk categories. The text 

does attempt to clarify the difference between these 2 categories: Those in the “Frequent” risk 

category are working in areas where rabies is common and those in the ‘Infrequent” risk 

category are working with terrestrial animals in areas where rabies is uncommon or rare. But the 

language was cumbersome and users found it difficult to understand. The important role that 

geographic location or surveillance data plays in determining risk was not clear. The “Frequent” 

category includes all persons who frequently handle bats and the “Infrequent” category 

mentions travelers visiting areas where rabies is common and immediate access to appropriate 

medical care is limited. Given that the application of the ACIP recommendations in the last 

column of the table is dependent upon the clarity here, the WG decided to make some changes. 
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The WG decided to split of the “Typical Populations” information into 2 columns, which are in 

the red box on the slide as shown here: 

In the row for the “Continuous” risk category, the “Disease Biogeography” is the laboratory and 

the “Typical Population” is “Laboratory personnel who work with live rabies virus in research, 

diagnostic, or vaccine production capacities.” There are examples provided upon which the WG 

elaborated, “necropsy of suspect rabid animal or working with rabies virus cultures.” Obviously, 

this population is at the greatest risk of rabies exposure, and the PrEP reflect that. For the 

“Frequent” risk category, there are 2 different populations who have a high enough risk for 

rabies to be included in the “Frequent” risk category. Both are based on the principle that if 

someone has frequent exposure to rabies, they fall into this category. In geographic regions 

where bats are the only reservoirs for rabies, the typical population is “Persons who frequently 

handle or comes into contact with bats (e.g., bat biologist).” In geographic regions where 

terrestrial mammals are reservoirs for rabies, people who work with these terrestrial animals are 

at “Frequent” risk. Those populations include “Animal care professions (e.g., veterinarians, 

technicians, animal control officers)” and “Others who repeatedly handle terrestrial reservoir 

species (e.g., wildlife biologists, rehabilitators, and trappers.” Persons with the same animal 

professions described here, could fall into the “Infrequent” category if the region where they 

work is one without terrestrial rabies.

That is seen in the first row of the “Infrequent” category. People can have professions that are 

similar to those in the “Frequent” category, but be listed in the “Infrequent” category as seen in 

the list in the “Typical Populations” column: Animal care professionals, Others who repeatedly 

handle terrestrial reservoir species, Spelunkers. Spelunkers was added to this row. This was 

previously in the “Frequent” category, but the WG felt that the recommendations for those in the 

“Infrequent” category might be a better fit. The second row in the “Infrequent” category includes 

“Geographic regions where terrestrial mammals are the reservoirs for rabies.” The population is 
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different from that of the “Frequent” category in that “veterinarian students” have less exposure 

than a veterinarian would. It also includes short-term volunteers. This also includes “shortterm/volunteer hands-on animal care workers where increased risk is expected for short time 

periods” and people for whom frequency of titer checks would not be as important as those who 

would fall into the “Frequent” category.

The third row for the “Infrequent” category includes “Geographic regions internationally with 

canine rabies.” The “Typical Population” here includes “Travelers who will be performing 

activities (e.g., occupational or recreational) that put them at increased risk for exposure to rabid 

dogs and may have difficulty getting access to safe PEP (e.g., in rural areas). Children may 

receive PrEP depending on the country to which they will travel (see CDC Traveler’s Health 

destination pages).” This all aligns with the soon to be updated CDC Traveler’s Health 

destination pages and the 2022 Yellow Book.

These are minor changes that were made to the table that are expected to clarify the contents 

and make it more user-friendly. The information in the last column is about PrEP schedules and 

the frequency of serologic titer checks is the subject predominantly of the next presentation. The 

WG made a few other changes to this table for clinical guidance. The minimal acceptable 

antibody titer level was changed to 0.5 IU/mL to ensure standardization with WHO and 

laboratories nationwide. The WG also recognized that the disease biogeography, because it 

was not its own column, may have created some confusion about the importance that should be 

placed on it and, therefore, highlighted the importance for local or state health departments to 

be contacted if there is any confusion about those issues.

In terms of vaccine series and frequency of titer checks, intradermal (ID) rabies vaccine 

administration has been globally recommended since the 1980s. WHO, as recently as their 

2019 recommendations, recommended ID because it is dose and cost-sparing. For that 

population, the population the WHO guidelines are for, dose and cost-sparing recommendations 

could make the difference between a person getting vaccine and not getting the vaccine. So 

potentially life or death in the case of PEP. However, the US population is a different population. 

In the US, rabies vaccine is not licensed for ID use. It is packaged for one intramuscular (IM)

injection. There is less of a need to vaccinate many people concurrently as there might be in 

developing countries, so the risk of infection that could come from multiple punctures to a vial 

that is intended to be a single use vial and therefore without preservatives, might not outweigh 

the benefits. Most of the populations for whom PrEP is recommended in the US are because of 

the work performed in their occupation. So presumably, occupations might pay the cost for 

these. For these reasons, the WG group preferred IM regimens.

The 2008 ACIP PrEP schedule is IM rabies vaccine on days 0, 7, and day 21 or 28. This is the 

schedule for all persons in the “Continuous,” “Frequent,” and “Infrequent” risk categories. The 

frequency of titer checks, however, differed depending upon the risk category. It was every 6 

months for those with the greatest risk to unrecognized exposures, and it was every 2 years for 

those in the “Frequent” risk category. For those in the “Infrequent” risk category, the guidance 

was that titers are not needed. Therefore, no PrEP or titer checks were recommended in the 

2008 recommendations for those in the “Rare” category. Rabies antibody titer is used as an 

indicator of adequate immune response to vaccine, but acceptable titer is not an indication of 

protection. It is a surrogate. A person with a low titer may still be immune. That person might 

very well still mount an anamnestic response if they had a rabies exposure. But because of the 

high mortality associated with rabies and the high risk for some populations, guidance has 

always been to try to maintain a higher than the minimum acceptable antibody titer level for 
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85

these people at their routine titer checks. A lower titer might still have protected them, but a

sustained higher titer is preferred.

Given all of this, the WG’s task was to: 1) evaluate whether vaccine series could be different 

depending upon the risk category by looking at data for a 2-dose IM series and data about a 

booster for those in the higher risk categories; and 2) evaluate whether frequency of titer checks 

could be different depending upon the risk exposure category by looking at data that helps 

determine whether titer checks for persons in the “Continuous” category should be more often 

than those in the frequent category. These data are the subject of the next presentation by Dr. 

Blanton.

Discussion Points

Dr. Hunter requested that Dr. Rao go back to the proposed table and walk him through what 

would be done for a bat biologist in an area that has geographic regions where terrestrial 

mammals are reservoirs for rabies.

Dr. Rao responded that anyone who is a bat biologist who is practicing in the US, for 49 out of 

50 states they would fall in the “Frequent” risk category. This would be “Geographic regions 

where bats are the only reservoirs for rabies” where she noted that the “only” is probably not 

needed.

Dr. Hunter agreed that removing the word “only” would be advisable.

Dr. Bell said she was interested to see the estimate that 15,000 people a year receive PrEP, 

which struck her as being a lot. She was curious about whether Dr. Rao had any information 

about what comprises the largest proportion of this group of people. It seems like there would 

not be a lot of turnover for a lot of these people that would require vaccination of that many 

people annually.

Dr. Rao said she thought most of them were occupationally associated. It is known that among 

these occupations, veterinarians have to get vaccinated as part of their veterinary schooling. 

Based on the many manuscripts published, some of the other professions are not as good 

about getting vaccinated and maintaining titer checks that are required. It is assumed that the 

highest categories are accounting for the most number, and probably not as many travelers.

With respect to indirect exposure, Dr. Sanchez said he was not aware that rabies was spread by 

droplet and wondered under what situations this might occur.

Dr. Rao indicated that there have been situations in which laboratorians have, through 

manipulation of a virus, been exposed to aerosolization of the virus. The people in the 

“Infrequent” category who get a bite or scratch, that would be a direct exposure; whereas, those 

who are manipulating the virus might be at risk in other ways. In a clinical situation, there is 

concern about people who experience droplet exposure through intubation. PrEP is not 

indicated for clinicians and no transmissions have ever occurred in the clinical environment. The 

type of exposure someone may have had to a case that eventually becomes confirmed for 

rabies is part of the post-exposure risk assessment.
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Dr. Fryhofer (AMA) noted that there are some very rural locations in parts of Georgia and she 

occasionally has patients who are hunters present to her office. A lot of times trappers send 

things to taxidermists, and taxidermists make things people put on their walls. She wondered 

whether there was any risk beyond the trapper for rabies.

Dr. Rao said she supposed if it were soon after the animal died and saliva was present on its 

nails or elsewhere, it could be a possible exposure. The risk would probably decrease once time 

had elapsed since the animal died. She had never heard of any kind of exposure in such a 

scenario.

Dr. Frey wondered how long a taxidermist waits to manipulate a dead animal or what they do 

with the neural tissue, brain and spinal cord, and at what point.

Dr. Petersen (SME) said that there is always the possibility that there could be transmission of 

rabies virus if there is saliva or other infectious material like neural tissue in contact with mucous 

membranes or any break in the dermal barrier. If that is documented, it would be indicated for 

PEP. However, at the same time, the rabies virus is not a very hardy virus. It can be killed by 

desiccation as well as UV light. Depending upon the state of the carcass, one could potentially 

determine the risk based on those factors. If it is dry, it is more than likely not a high risk. All of 

those types of risk assessments can be done on a case-by-case basis.

Dr. Rao added that would be primarily PEP versus PrEP.

Systematic Review: Rabies Pre-Exposure Prophylaxis Immunogenicity

Jesse Blanton, DrPH

Co-Lead, ACIP Rabies WG

Epidemiologist

National Center for Emerging and Zoonotic Infectious Diseases

Centers for Disease Control and Prevention

Dr. Blanton described the rabies PrEP systematic review and meta-analysis that CDC has been 

working on with the WG. As a way of orientation, he first spoke about the broader systematic 

review activity that was done and then focused specifically on the meta-analysis that was done 

with respect to the 2-dose vaccination series.

The systematic review was conducted looking at the immunologic response to rabies PrEP with 

a focus on the primary response, duration of immunogenicity, and the response to booster

vaccination. The systematic review was started in 2017 and then updated through 2019. The 

population was very broad, including any persons with the potential for rabies exposure. The 

interventions included: 1) Persons receiving alternate rabies vaccination schedules using 

modern cell-culture vaccines; and 2) persons receiving rabies vaccination by alternate routes 

using modern cell-culture vaccines, primarily ID. The comparison was the gold standard ACIP 

recommendations, which is the rabies PrEP 3-dose, 3 to 4 week schedule by the IM route using 

modern cell-culture vaccines. The outcomes include rabies neutralizing antibodies reported as 

IU/mL 1 to 3 weeks after primary vaccination, 1 year post-vaccination, and after booster. 

The literature search included examination of multiple databases (MEDLINE, Embase, 

Cochrane Library, WHO Index Medicus, citation sampling) for the period from January 1965 

through December 2019. This represents the period during which modern rabies vaccines were 

either under study or available. The search terms included: (rabies OR rabies vaccine) AND 
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(antibodies) AND (human) AND (preexposure OR pre-exposure). The search resulted in 

identification of 258 unique papers. The exclusion and inclusion criteria included:

Exclusion Criteria

 Use of nervous tissue or experimental vaccines (not a licensed vaccine or ever evaluated by 

WHO)

 Immunocompromised populations

Inclusion Criteria

 Subjects received PrEP (schedule of 1-3 doses over any form of a schedule) 

 Immune response to vaccination measured by Rapid Fluorescent Focus Inhibition Test 

(RFFIT), the gold standard neutralization assay

 Findings reported as geometric mean titer (GMT) (IU/mL) or as a seroconversion rate to a 

stated cut-off (e.g., 0.5 IU/mL)

Screening and critical review of the 258 papers resulted in 63 publications total accepted for 

review, ranging from 1978 through 2019. These included a total of 146 cohorts or study arms 

and 11,608 subjects who were involved in the selected studies. The study types, geographic 

locations, schedules, vaccines, and routes of administration included the following:

Study Types

 Randomized clinical trial (59%)

 Controlled clinical trial (16%)

 Cohort study (13%)

 Case/Time series (12%)

Study Locations

 Asia (41%)

 North America (29%)

 Europe (25%)

 South America (3%)

 Africa (2%)

Schedules (Cohorts)

 Single dose

 2-dose: day 0,28; day 0,60; day 0,7

 3-dose: day 0,3,7; day 0,7,14; day 0,7,21/28

Vaccines (Cohort)

 Purified Vero Rabies Vaccine (PVRV, broad utilization internationally) 

 Purified Chick Embryo Cell Vaccine (PCEC) 

 Human Diploid Cell Vaccine (HDCV) 

 Others

Route (Cohorts)

 Intramuscular (IM) 

 Intradermal (ID) 

 Subcutaneous (SC) 
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Broadly for this overall systematic review what was found looking at the general schedules was 

that from a primary vaccination response, there really was no significant difference in the 

seroconversion rates between the various schedules. The WG focused on the Day 0, 7, one 

week schedule, which is easy to administer because it involves fewer doses and is also 

concurrent with the new WHO recommendations. To offer a broad perspective of the metaanalysis of the existing 3-dose schedule (0, 7, 21/28 days), , this schedule is very wellestablished with more than 40 years of experience. There is very high (>97%) seroconversion 

after vaccination with a 3-dose schedule, regardless of vaccine or administration route, and a 

nearly 100% seroconversion rate 1 to 2 weeks after vaccination.

In terms of the comparison for the GMT for this schedule, there is a considerable amount of 

heterogeneity or variability between the studies for the GMT for vaccination. Looking at 

differences between IM and ID studies on the 3 dose/3 to 4 week schedule, IM produces 

significantly higher GMT, but the relative clinical difference between the significant difference is 

somewhat questionable. While the seroconversion at 0.5 IU/mL is not necessarily a protective 

level, it is recognition that this is an adequate immune response, and that a person who has an 

adequate immune response can receive a booster that generally is protective against rabies 

challenge. While the WG is not looking at the ID schedule currently, some ID studies were 

utilized later in the analysis because they did not want to exclude those data in an area where 

there are relatively few studies for some of the other schedules.

In terms of the rabies PrEP 2-dose, 1 week Schedule (day 0 and day 7), looking at primary 

response, of the larger systematic review, 12 total studies provided information that could be 

used for the pooled analysis for the 2-dose schedule, which are depicted in the following table:

One of the things that had to be done was that because these clinical trials do not have any 

direct ratio comparison internally, it was determined that these study arms could be broken 

apart and treated as more of an observational cohort for this pooled analysis. While the original 

studies were controlled trials, the individual study arms were treated from more of an 

observational perspective. That allowed for removal from these studies some of the individual 
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study arms that either were not the schedule of interest or included vaccines not licensed in the 

US. Another advantage of looking at the 0,7 schedule in the primary study is that this is the first 

two-thirds of the 3-dose schedule. For studies that can provide information and serological data 

on Days 14, 21, 28 before the third dose is received, is information that can be assessed for the 

primary response to the first 2 doses of vaccine. The last two studies in orange (i.e., the last two 

rows of the above table), Soentjens and Endy, looked exclusively at comparisons of the 2-dose 

vaccination schedule to the 3-dose.

In terms of the serologic response, the GMT among individuals who received only 2 doses of 

vaccine on Days 0 and 7, there was kinetics growth and antibody response between the groups. 

It is important to point out that there are a limited number of studies, but similar heterogeneity as 

observed in 3-dose ACIP meta-analysis. There is a robust response moving up to nearly 10

IU/mL within 1 to 2 weeks after vaccination and 12 IU/mL in the subsequent week. Looking at 

the seroconversion rates (SCR), very consistent results are reported across the different 

schedules at 1 to 2 weeks after the second dose and 3 weeks after the second dose. High SCR 

(98%) were achieved 7-14 days after the second dose (Day 7). 

Dr. Blanton presented a slide comparing the response 30-60 days after the [0, 7, 21/28] 

schedule and the [0, 7] schedule. seroconversion in these groups. From a serology standpoint, 

we see 100% seroconversion in these groups 1 to 2 months post-vaccination. Again, the 

limitation is the small number of studies that were available for some of these analyses.

In terms of the data for the duration of immunogenicity and the response to booster, 13 studies 

had information available for this analysis, removing some of the individual cohorts that were 

using non-US licensed vaccines:

Looking at this beginning with the response in individuals 1 year post-vaccination, there was no 

significant difference between the 2-dose and 3-dose schedules looking at the GMT 1 year out. 

However, looking at serology at 1 to 2 weeks after the booster dose (i.e., booster given 1 year 

after the 2 dose series) there was a significantly higher anamnestic response in the 3-dose 
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group versus the 2-dose 0,7 schedule. Again, both of these are high above the minimal 0.5 

IU/mL. The difference is again somewhat questionable in terms of clinical significance. In terms 

of the SCR, the opposite scenario is observed in which for the individuals who received a 

booster 1-year post-vaccination, the 2-dose group experienced a more rapid decay in the 

number of individuals with an adequate immune response. About 60% of individuals who 

received 2 doses still had an adequate response at 1 year compared to 90% amongst those 

who had received 3 doses. However, there is a complete universal anamnestic response postbooster dose in all individuals boosting above the minimal level.

Dr. Blanton summarized these studies individually, looking at the two primary studies that 

provided information on the serological response. Soentjens et al. (n=183) was administered 

entirely ID, it was one of the larger sample sizes. They found that amongst the individuals who 

had pre-booster serology taken in a 1 to 3 year window, the 2-dose ID group had a significant 

higher GMT (3.4 IU/mL) compared to those who received 3-dose ID (2.0 IU/mL). Again, as seen 

with the other data, 100% of both groups had an adequate titer (>0.5 IU/mL) after booster. Endy 

et al. (n=22) presented data on both 2-dose and 3-dose by IM and ID administration and 

similarly found no significant difference in the GMT at day 365 for 2-dose IM or 2-dose ID. Of 

the recipients, 40% to 50% of 2-dose recipients had a titer of >0.5 IU/mL at day 365, but 100% 

of recipients had an adequate titer after receiving booster at 1 year. 

In terms of the larger systematic review, given the time that the 3-dose, 3 to 4 week schedule 

has been utilized, there has been more time to assess the long-term kinetics of the antibody 

response with this series. This also has been found in shorter time periods with some other 2-

dose 0,28 day schedules. Most studies evaluating the 3-dose (0,7,21/28) schedule (IM and ID) 

found that there is a rapid decay during the first 6 months post-vaccination that slows to plateau 

between 6 months to 1 year. The decay has been found to be more rapid when administered by 

ID route. More importantly, the studies have generally found that in situations where a booster 

dose is administered at around 1 year, there is a greater increase in titer than what was 

observed in the original primary response amongst individuals, and that there is a slower decay 

after booster is received [Banga et al. Vaccine. 2014; 32:979; Brown et al. Vaccine. 2008; 

26:3909; Mansfield et al. Vaccine. 2016; 34:5959; Strady et al. JID. 1998; 177:1290].

This also could be seen with some of the systematic review meta-analyses in which individuals 

are assessed who do not receive a booster dose at 2 years. These generally found that only 

about 85% are reported with an adequate titer at that time period (seen largely in cohorts of 

veterinary students) compared to individuals who do receive a booster at 1 year and tend to 

maintain much higher adequate antibody rates in excess of 95% over long periods of up to 4 to 

5 years in some of these studies conducted over longer time periods.

This is just some of the information the WG is assessing in relation to the 2-dose schedule and 

consideration of recommendations pertaining to boosters for higher risk groups, which will allow 

for the extension of serological monitoring periods for the various risk groups.

Discussion Points

Dr. Hunter asked whether the first dose of a PEP could be considered as the booster for a 2-

dose PrEP series. The way he was thinking about this from a clinical and public health response 

was that first. Someone needs to be in a situation in which they should receive the PrEP due to 

having ongoing exposures. The individual would then need to recognize that there was an 

exposure, and be in place that is not in the bush and PEP can be obtained. The question 

regards what amount of time one has from the point of recognition of exposure to when the 
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amnestic response is needed, and whether enough will be achieved from the first dose of PEP 

in time for protection.

Dr. Frey responded that part of the question requires that one be aware of the exposure and 

then seek follow-up. The incubation period for rabies is complex and the estimates are rather 

broad. The idea is that once there is an exposure, immediate attention should be sought. That 

could be difficult in the bush because it could be weeks or longer before getting aid. The other 

issues regards whether product is available when aid is sought. Whether the PEP dose is 

sufficient to boost the PrEP depends upon the period of time since exposure and how quickly 

someone can acquire the PEP. Those who are going into such a situation have to think 

differently about their PrEP.

Dr Bell said she always found the deliberations about the schedule for a vaccine such as rabies 

in which the mortality is pretty much 100% and there is no way to evaluate efficacy to be very 

challenging. The idea of shortening the schedule is also challenging. Given the issue of 

boosters for those who have received PrEP and ensuring that they do not miss their boosters so 

that they maintain their titers in a safe zone, it perhaps becomes more important to continue to 

have this margin of safety for people who have ongoing exposure. This is like a coverage 

question about which there are probably no data. However, she expressed interest in hearing 

Dr. Blanton’s anecdotal sense of the extent to which the populations that are covered with 

existing PrEP recommendations are compliant with getting the recommended booster doses.

Dr Blanton responded that it is difficult to determine who is getting the booster doses. There 

generally has not been great compliance with serological monitoring. Large segments of the 

veterinary population, who are probably the best tracked, are not getting serological monitoring 

over these time periods and have populations of 20% to 30% who no longer meet the minimum 

titer level such that they would be recommended to receive a booster dose. The anecdotal story 

of that is that there have never been reported cases of failure in those populations.

Dr. Talbot observed looking at Slide 14, it appears that this is really based on the study with 22 

patients. That is concerning to her because that is a very small number and this is a fatal 

disease. This is an instance in which the vaccine is known to be safe and 200 people could be 

recruited, given 2 doses, and followed over time to collect some really nice data. This does not 

have to be an elaborate study. Along those lines, it is time to obtain the data on how many 

veterinarians in high risk settings are getting repeat vaccinations and serology. That is a study 

that could be done working with the veterinary associations and other groups. These data are 

needed for ACIP to make a decision, particularly since this is a 100% fatal disease.

Dr. Frey agreed that there are a lot of studies that could or should be done in this field to 

answers those types of questions. Laboratorians are routinely checked every 2 years, and their 

levels are maintained at above 0.5 IU/mL. Veterinarians are fairly good about having their titers 

checked. Those who are not as good about it are the ones who might be at risk also for 

unknown exposures like the laboratorians.

It seemed to Dr. Bernstein that after 50 years of literature, there appeared to be some instances 

in which one vaccine might be preferred over the other. It sounded like duration was better with 

the IM than the ID administration route. He wondered whether people would prefer to use an IM 

rather than an ID initially.
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Dr. Blanton indicated that there has been quite a bit of research assessing that. Generally, the 

ID route tends to have a slower decay than the IM over long periods. However, the relative 

clinical implications of that are not clear. While statistically significant, the implication for 

protection is not well-understood. More is better depending upon the type of exposure and 

contact one has, and the difference between ID and IM is probably negligible in terms of the 

difference of decay. Both routes have a very solid anamnestic booster response for that 

reaction. The ID route has been used pretty extensively throughout the rest of the world, and 

there is no real difference in failure rates and such has ever been observed with the ID route. A 

lot of issues regard the practical side of having enough vaccine throughout in the clinics to be 

able to reasonably use vials in a timely manner.

Dr. Talbot emphasized the need to conduct the suggested studies, particularly if ACIP was 

being asked to reduce the number of doses. Real data are needed. She is not comfortable 

changing a schedule for a 100% fatal disease without the data.

Dr. Atmar agreed and also would be concerned about the paucity of data for the IM route, which 

is essentially what they would be addressing for the US in terms of the potential ACIP 

recommendations to be made. Although it is likely that the ID will translate over, the fact is that 

based on the data presented, it appears that there are considerably less than 100 persons from 

whom the data on primary responses were obtained. That did not instill confidence about what 

the actual rates may be in terms of seroresponse or GMTs.

Dr. Bell added that she also had a certain level of discomfort with the idea of shortening the 

schedule that saves a dose of vaccine for approximately 15,000 people a year. To say that it is 

probably okay in this type of situation in which it also seems like compliance with booster doses 

is not great does not seem judicious. She would like to understand the rationale for reducing the 

doses in a situation where the potential adverse consequences are large.

Dr. Hunter pointed out that ACIP is likely to be faced with the situation that occurred with 

meningococcal B vaccine, which is a very severe sequalae without much data because of the 

low frequency of the disease.

Dr. Frey indicated that the WG is talking about a 6-month to 12-month booster in some 

populations, which ACIP would hear more about.

Clinical Guidance and Next Steps

Agam Rao, MD FIDSA

CDR, United States Public Health Service

National Center for Emerging and Zoonotic Infectious Diseases

Centers for Disease Control and Prevention

Dr. Rao emphasized that the revised table she reviewed earlier represented a good amount of 

the clinical guidance the WG worked on. As previously mentioned, the “Disease Biogeography” 

and “Typical Population” columns were modified somewhat, mostly to improve clarity but also to 

align with CDC Traveler’s Health Guidance and to provide more examples so that a provider 

has more information and can extrapolate it to the specific situation of the patient in front of him 

or her. Other guidance is the change in the minimal acceptable antibody level to 0.5 IU/mL, and 

the repeated advice to contact local or state public health for advice if unsure which mammals 

circulate in a specific region. The last column of this table will be completed once the GRADE 

and EtR of the data Dr. Blanton presented earlier are presented to ACIP in June 2020. 
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Because those recommendations could be different for special populations, the WG looked at 

data about the effectiveness of rabies PrEP for special populations. Children, however, 

exhibited a robust response—even better than healthy adults. Therefore, the WG does not 

anticipate needing any special considerations for children. For persons with altered immunity, 

studies found varying immune responses. As mentioned in ACIP’s “Altered Immunocompetence 

Guidelines,” effectiveness, but not safety, is of concern for inactivated vaccines like the rabies 

vaccines. The 2008 ACIP recommendations specifically state, “Patients who are 

immunosuppressed by disease or medications should post-pone pre-exposure vaccinations and 

consider avoiding activities for which rabies Pre-exposure prophylaxis is indicated. When that is 

not possible, immunosuppressed persons who are at risk for exposure to rabies should be 

vaccinated and their virus neutralizing antibody titers checked.” That is different from healthy 

patients in whom titers are not routinely checked after completion of a PrEP series.

There are data about effectiveness of PEP, but not PreP, in pregnant persons. The current 

ACIP recommendation states, “If the risk for exposure to rabies is substantial, PrEP might be 

indicated during pregnancy.” The WG’s preference was to state that there is no safety or 

effectiveness concerns for PEP administration in pregnancy, and that the decision to perform 

activities that would necessitate receiving PrEP during pregnancy is an individual decision.

A consideration for travelers was the co-administration of rabies vaccines with malaria 

prophylaxis. In the 1980s, there was a report of a Peace Corps worker who received ID PrEP + 

chloroquine, and was later bitten by a dog but did not receive PEP and ended up passing away 

from rabies. Her rabies antibody levels at the time of her eventual hospitalization were found to 

be low, raising the question of whether antimalarials interfere with immunity from rabies vaccine.

The 2008 ACIP recommendations lumped antimalarials in a sentence with immunosuppressive 

agents by stating that, “Corticosteroids, immunosuppressive agents, antimalarials... can 

interfere with development of active immunity after vaccination.” While there was no specific 

guidance for what to do if this were the case with antimalarials, the paragraph did go on to make 

the statements about the immunocompromised states that Dr. Rao mentioned earlier.

The WG reviewed a 2019 study published in the 1

Journal of Infectious Diseases that compared 

ACIP’s PEP IM schedule after initiation of chloroquine, Malarone, and doxycycline and found 

that co-administration of Malarone resulted in high antibody titers. For the arm involving 

chloroquine, the antibody levels were lower but were still 4 times higher than the minimum 

antibody cut-off (i.e., the lower antibody levels are not clinically significant). The WG’s 

preference is to remove antimalarials from the sentence about immunocompromising conditions 

since all antimalarials do not have an effect on active immunity, and instead state that titers may 

be considered for persons vaccinated while concurrently taking chloroquine, regardless of 

whether the chloroquine is for antimalarial prophylaxis [1

Endy TP, Keiser PB, Cibula D et al. J 

Infect Dis. 2019 Nov 2].

In terms of next steps, some of these items may be revisited given the discussion that was 

raised during Dr. Blanton’s presentation during this session. For now, Dr. Rao presented what 

had been planned. The Rabies WG developed 2 policy questions for PrEP topics. The first is, 

“Should a 2 dose pre-exposure prophylaxis (PrEP) series involving HDCV or PCECV IM [0, 7 

days] replace the 3 dose series IM] 0, 7, 21/28 days] for all those for whom rabies vaccine PrEP 

is recommended?” The population is persons for whom rabies vaccine PrEP is recommended, 

the intervention is [0, 7 days] rabies vaccine PrEP schedule, and the comparison is [0, 7, 21/28 

days] rabies vaccine PrEP schedule. There was only one outcome, which is immunogenicity.
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Safety was not included as an outcome given the review of safety data that Dr. Rao presented 

earlier.

The second policy question is, “Should an IM booster dose of rabies vaccine (PCECV or HDCV) 

be recommended 6-12 months after the 2 dose pre-exposure prophylaxis (PrEP) series IM [0, 7 

days] for those in the continuous and frequent categories of people who receive PrEP?” The 

population is persons in the “Continuous” and “Frequent” categories for whom rabies vaccine 

PrEP is recommended. The Intervention is 6-12 months rabies vaccine booster after [0, 7 days 

rabies vaccine PrEP schedule. Here as well, the WG identified only one outcome—duration of 

effective immunogenicity. 

For the June ACIP meeting, the WG will give the last PrEP presentation which will be the PrEP 

GRADE and EtR presentation. They also will be presenting data about PEP, with a plan to 

present the background about PEP considerations and data to inform recommendations and 

guidance about PEP including the PEP vaccine series, the newly licensed rabies immune 

globulin products, location of RIG administration, and PEP considerations for special 

populations.

For future meetings, the WG will present clinical guidance about handling deviations in PrEP 

and PEP and clinical guidance about managing completion of a PEP series after it is initiated 

internationally and with vaccines not available in the US. The WG also took the suggestion that 

the committee gave to them during the October 2019 meeting and plan to introduce a flow chart 

that depicts what has previously only been included in text about PEP. The flow chart will be a 

visual depiction of the various factors that providers should consider when deciding whether 

PEP is indicated for a specific patient. In addition to the clinical guidance, meetings in October 

2020 and February 2021 might involve votes for the PrEP and PEP policy questions. All of this 

is subject to revision, given the questions raised during Dr. Blanton’s presentation. 

Discussion Points

Dr. Atmar said he was always confused about the 2 levels of seroprotective titers, but his 

recollection was that 5 IU/mL was used previously and WHO used 0.5 IU/mL. While he 

understood the desire for alignment, the rationale for the higher level being used up to this 

change and the implications it might have for interpretation of the chloroquine data was not 

clear. He requested a reminder of the prior threshold used and what data there are other than 

the desire to align with WHO this many years later.

Dr. Rao indicated that the recommendation as it stands now is complete neutralization at less 

than 0.5 IU/mL. By adopting 0.5 IU/mL, it is actually a higher titer level and the populations who 

would be affected would be those in the highest risk category (laboratorians, animal care 

workers near terrestrial or bat rabies). It would not be a lot of people.

Dr. Hunter wondered what would occur if the policy question were 0,7 and then 21 days to a 

year/anywhere in that range, for the third vaccine. It seems that there would be clinical and 

timeline implications for the analysis.

Dr. Rao asked whether he was suggesting this for only the people in the highest risk categories

or for people lower down the list, such as international travelers.

Dr. Hunter clarified that he was thinking of all of them.
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Dr. Rao indicated that earlier in the WG’s process, they thought about perhaps keeping the 0, 7, 

21 regimen for the highest risk categories but dropping down to a 0,7 schedule for the lower risk 

categories. The reason being that it is known from the data that for someone with short-term 

summer volunteer work experience with animals, the duration of a high titer is less important 

and a 0,7 schedule would suffice. However, it was starting to get somewhat hairy. For example, 

if someone is in the lower risk category but then changes professions to a higher risk category, 

it was not clear what to recommend for them. Part of the thought process for this booster dose 

being okay is that for people in the highest risk categories, their occupational health clinics 

should be enforcing it (laboratorians, veterinarians, wildlife workers). This is similar to ensuring 

that they receive the third dose at 21/28 days to ensure that they get it 6 to 12 months later, 

which the WG did not think would be much of a problem and would not be needed for the lower 

category of people. However, they had not thought about 21 days to 1 year. For travelers, it is 

known that the 21-day issue creates problems because people do not think beforehand about 

getting the entire vaccine series.

Dr. Frey added that one of the problems with travelers is they wait until almost too late to get the 

full series in. One of the considerations with the 0,7 day vaccination schedule was that travelers 

could accomplish that better. Some data showed that 0, 7, 21/28 day antibody titer response 

was somewhat better than the 0,7, 28, but it was not significant. For the high risk continuous risk 

folks, the idea is to keep the measurable level at 0.05 IU. The lowest level of protection is 

unknown, but 0.05 IU is known to be protective. Any boost further out gives a nice increase in

GMTs.

In terms of the rationale to reduce the number of doses so that travelers can get them in, Dr. 

Cohn pointed out that there are other traveler recommendations. Therefore, she cautioned them 

not to change the recommendation just so that travelers can complete the dose. It would be 

preferable to provide guidance for them.

Dr. Frey clarified that the WG was not suggesting changing the schedule because of that. It was 

just a consideration. 

To summarize some of the concerns, Dr. Lee observed that it seemed like a better 

understanding of implementation considerations might be useful (adherence to serologic testing, 

booster doses). Thinking about private practitioners and veterinarians, if someone is part of a 

health system, clinic, or animal control, it seems like there should be more routine regulatory 

standards to make sure protection is enhanced for that population.

Dr. Bell said she would like to better understand the rationale for the proposed changes, given 

that it was unclear whether anything actually needed to be changed. 

Dr. Poehling thought it would be helpful to know which categories the 15,000 doses 

administered fall into.

Dr. Frey called on their public health colleagues to share information about what happens in 

their practices or what concerns they have.

Dr. Bahta said that while she had not worked with their rabies team recently, most of their work 

is in PEP. Therefore, she did not think they could speak to PrEP.

Dr. Cohn asked whether anyone was present from the company who could speak to where 

doses are distributed. 
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Dr. Ritchey (Sanofi Pasteur) and Dr. Leonard (GSK) indicated that they did not have specific 

data readily available to provide on distribution, but would obtain details and report back to ACIP 

at a later time.

Dr. Finley (AIM) indicated that in their area, they are aware that veterinary technicians are often 

not covered. There are private clinics that administer ID three times to try to meet it, because it 

is one-third the price. Cost is a major issue and vaccination is not always occupationally 

covered. They know it is not ACIP-recommended, but it is the best they can do to be protected.

Dr. Rao observed that perhaps a 2-dose series administered IM would be better accepted by 

such groups versus maintaining a 3-dose series via an ID route, and could be a potential 

consideration.

Dr. Hahn (CSTE) mentioned anecdotally that in Idaho, there are often exposures in veterinary 

offices. They are treating ill dogs and cats, and she is surprised at how often the staff are not 

vaccinated. She does believe that cost is probably part of that consideration. She would have 

assumed vaccination to be routine, but that does not appear to be the case in Idaho where there 

are no terrestrial rabies.

Introduction

Robert Atmar, MD

Chair, Dengue Vaccines WG 

Advisory Committee on Immunization Practices

Dr. Atmar reviewed the Dengue Virus WG discussions from November 2019-February 2020, 

which included the following:

 Dengue Vaccination in the Philippines: Unintended Consequences 

 Review of October ACIP Dengue Vaccines Session

 ACIP Dengue Vaccines Work Group Informal Poll

 CYD 65, DENGVAXIA® Efficacy Follow-Up Study

 Partnership for Dengue Control Pre-Vaccination Screening Workshop Update

 Puerto Rico Dengue Vaccine Knowledge and Attitudes

Dr. Atmar indicated that presentations would be provided on the following topics during this 

session: 

 Dengue Vaccine Knowledge and Attitudes in Puerto Rico

 WHO Global Recommendations on Dengue Vaccination

 Summary of WG Discussions and Next Steps

In terms of future WG plans, topics for the June 2020 meeting include a CDC assessment of 

laboratory tests for pre-vaccination screening, with a possible additional cost-effectiveness of 

CYD-TDV presentation during the June 2020 meeting. Plans for the October 2020 meeting are 

Dengue Virus Vaccine
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to present the Evidence to Recommendations (EtR), and possibly draft CYD-TDV 

recommendations. 

Dengue Vaccine Knowledge and Attitudes in Puerto Rico

Ines Esquilin, MD

University of Puerto Rico 

School of Medical Sciences 

Department of Pediatrics

Dr. Esquilin presented data on dengue vaccine knowledge and attitudes data from Puerto Rico. 

This information was obtained from 3 sources including the general population, physicians, and 

parents of children 9 through 16 years of age. The general population data come from a 

household survey conducted in Puerto Rico. The physician data collection was sponsored and 

guided by the Puerto Rico Academy of Pediatrics. The opinions of parents of children 9 through 

16 years of age come from focus groups conducted by the Behavioral Science Team of the 

Centers for Disease Control and Prevention (CDC) Dengue Branch in San Juan.

The general population data were obtained from a community-based cohort study implemented 

in 2018 known as Communities Organized to Prevent Arboviruses (COPA). The participants 

were recruited from selected households in 38 cluster areas. A total of 1139 adults participated 

in COPA. When asked if they would receive the dengue vaccine for free, 73% said they would 

receive it for themselves and 75% said they would administer it to their children. Among the 

same adults, 63% said that they would pay for the vaccine for themselves and 68% said that 

they would pay for it for their children. When interest in the dengue vaccine among adult 

participants in COPA was explored, 59% said they would pay $10 per dose, 37% would pay $20 

per dose, and 12% would pay up to $50 per dose.

When asked for the reasons for not wanting the vaccine or for being unsure about it, only 1% 

were not worried about getting dengue. There was a lack of information about the vaccine since 

22% of the participants could not state a reason and 9% needed more information. Of the 

participants, 38% were worried about side effects/reactions. When they were asked about the 

most important feature of a dengue vaccine, most participants were concerned about the high 

level of protection at 66% among participants who said they would receive the vaccine versus 

50% of those who would not or were unsure if they would receive the vaccine. Concern about 

minimal side effects was more common in participants who were unsure or not willing to receive 

the vaccine at 33% versus 17% in those willing to receive it.

In terms of the survey conducted among physicians in Puerto Rico, 115 physicians completed 

the survey. Of those, 81% were practicing pediatricians or pediatricians with a sub-specialty. In 

terms of the methodology, a pediatrician from the CDC Dengue Branch gave presentations to 

the local pediatric associations during their Fall and Winter continuing education meetings from 

September 2019 through February 2020. Physicians were asked to complete the survey after 

the presentation. The survey included an informational bar graph on the risk of hospitalization 

and severe illness in vaccinated seronegatives, and the implications of pre-vaccination test 

specificity. Additional surveys were provided to pediatricians in the San Juan metropolitan area. 

The University of Puerto Rico School of Medicine Department of Pediatrics was provided with a 

copy of the CDC presentation, published literature on CYD-TDV, and available laboratory tests 

for pre-vaccination screening. 
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Regarding the results, only 31% of the 110 physicians who responded indicated that they 

administer vaccines in their office. Most vaccines are administered at private or public 

immunization clinics on the island. Of the responding physicians, 98% acknowledged that 

dengue is a significant public health problem in Puerto Rico. Only 58% of physicians knew that 

there was an FDA-approved dengue vaccine, 40% knew that the schedule requires 3 doses and 

48% did not know. Only half (59%) of the physicians answered the question on the efficacy of 

the vaccine and 54% stated that they do not know the approximate efficacy. The answer to the 

question pertaining to the percent of false positive tests the physicians were willing to accept 

was distributed between 0% to 5% of false positives for 54% of physicians, while 35% were not 

sure. Assuming that a laboratory test with acceptable specificity were available, 73% of 

physicians said they would recommend the vaccine and 21% were not sure.

Of those who would recommend the vaccine, 96% think that dengue is an important public 

health problem in Puerto Rico and that a reasonably effective vaccine is available for 

seropositive persons and 40% think that laboratory testing sufficiently reduces the possibility of 

vaccinating subjects with a false positive laboratory result. Of those unsure or unwilling to 

recommend the vaccine to their pediatric patients, 71% had concerns about the risks of 

vaccinating persons with false positive dengue laboratory results and 75% needed more 

information.

For patients diagnosed with dengue, 43% of physicians have documentation of a positive 

laboratory test in the medical record for some of their patients and only 5% have this for all of 

their patients. Physicians established that the necessary steps to enable a vaccination program 

for children in Puerto Rico include the Vaccines for Children Program (VFC) and private 

insurance coverage for the vaccine, and insurance coverage of the laboratory test for detection 

of past dengue infection. If insurance coverage for vaccine and laboratory tests were not 

available, 54% of physicians would still recommend the vaccine for private patients whose 

parents could pay for an approved laboratory test and the vaccination. However, 30% were 

unsure. If a recommended rapid diagnostic test for past dengue infection were available, 66% of 

physicians would support changes in Puerto Rico laboratory regulations. This is to allow such a 

test to be performed in the medical office, so that the first dengue vaccination would not require 

two or more patient visits. Most physicians (76%) would favor a pilot project with a phased in 

approach of dengue vaccination before implementing a large-scale program on the island.

A total of 38 participants were involved in the focus groups with parents of children between 9 

and 16 years of age, of which 87% were mothers. The objectives of the focus groups were to: 1) 

assess acceptability of the vaccine; 2) determine barriers to and motivators for a dengue 

vaccination program; and 3) identify knowledge, attitudes, and beliefs towards vaccines in 

general. In terms of the methods, focus group discussions were conducted in 3 municipalities 

with a high dengue incidence (San Juan, Carolina, and Ponce). The sample was comprised of 

parents of children between 9 and 16 years of age who were recruited from pediatrician offices, 

the WIC (Women, Infants, Children) Program, schools, and the Boys and Girls Clubs of Puerto 

Rico. It is important to note that 63% of those parents had at least one year of college education 

and 33% had completed a Bachelor’s or Master’s Degree.

Prior to asking the questions a script was read with information about the dengue vaccine and 

doubts about the script were clarified for the participants. In terms of general opinions about 

vaccines, most participants had questions about having a dengue vaccine. They had positive 

opinions about vaccines in general, but some of them decided not to receive the influenza 

vaccine and were concerned about issues such as the influenza vaccine changing every year 

and efficacy. Some distrust some of the new vaccines and others had concerns about allergic 
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reactions and autism as a result of vaccination. In terms of opinions about dengue vaccine, 

most participants have questions and a few had mixed opinions about this vaccine. Some would 

wait to see the effects on other children and others do not find it necessary to have a dengue 

vaccine at this time. Almost all participants did not know about the dengue vaccine. In terms of 

willingness to vaccinate, 38% of parents said they would vaccinate, 30% would not, and 32% 

were unsure.

The barriers to vaccine program participation identified within this group included lack of or 

inconsistent information, high cost and lack of insurance coverage, time-consuming laboratory 

tests, side effects, laboratory test results not being 100% reliable, approval for use only in US 

territories, sickness at the time of vaccination, and low effectiveness of the vaccine. The 

motivators for vaccine program participation identified included: provision of correct vaccine 

information, information about dengue and statistics in Puerto Rico, prevention of future dengue 

infections, support from the Puerto Rico Department of Health (PRDH), laboratory confirmation 

of previous dengue infection, an epidemic, educational forums. Most participants would pay a 

deductible for the vaccine, but would prefer it at no cost. An acceptable insurance deductible for 

insurance participants would range from $5 to $20 and an acceptable cost without insurance

would be about $50 to $80. 

All participants wanted more information about DENGVAXIA® and about the test to confirm past 

dengue infection. They have multiple questions, including:

 Why is the vaccine specific for children between 9 to 16 years of age? 

 Where have clinical trials taken place and what were the results? 

 What does the process of approval involve and how long does it take?

 What type of vaccine is DENGVAXIA® and what are the components?

 What is the dosage and how many time does it have to be administered? 

 What is the percentage of effectiveness?

 What is the evidence of short- and long-term side effects and how to treat side effects? 

 Are there any possible interactions with previous medical conditions or medications?

 How does the vaccine react if people get vaccinated and later have dengue again? 

 What countries are using the vaccine?

 Why is it approved for US territories only? 

 Does the Puerto Rico Department of Health require the vaccine?

 What dengue tests are required and how accurate they are? 

Participants stated that a culturally appropriate informed consent should include information 

about:

 Vaccine safety and effectiveness

 Confidentiality

 Specify laboratory test requirements prior to vaccination

 Specify consequences if vaccinated without a previous dengue infection

 Benefits and risks of vaccination

 Specific short-term and long-term side effects of the vaccine (i.e., if it could cause fever, 

headaches)

 Results from previous clinical trial studies with number of participants in the trials and 

percentage of effectiveness

 Information related to consent to be written in plain language and to be clear and concise 
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They all recognize that the best sources of information will include doctors (specifically 

pediatricians), nurses, the Academy at the University of Puerto Rico (UPR) School of Medicine 

at the Medical Sciences Campus, and CDC.

In conclusion with regard to the general population, participants demonstrated interest in the 

dengue vaccine among most adult participants for themselves and their children. Side effects 

and possible adverse reactions were the most important reason for those not wanting to receive 

the dengue vaccine. Among adult participants willing to receive the dengue vaccine, a high level 

of protection and minimal side effects were the most important features.

The conclusions from the physician knowledge and attitudes survey, most participants were 

pediatricians and only 30% of them administer vaccines at their offices. Almost all physicians 

recognize that dengue is a significant public health problem in Puerto Rico, but 43% were not 

aware that there is an FDA-approved dengue vaccine. Further physician education is needed 

regarding DENGVAXIA® vaccine, its schedule and efficacy, and safety. Most physicians would 

recommend the vaccine if a laboratory test with acceptable specificity were available to 

document prior dengue infection. Medical record documentation of past positive dengue 

laboratory diagnostic tests for patients is limited. Most physicians view the necessary steps to 

establish a vaccination program in Puerto Rico to include VFC and private insurance company 

coverage for the vaccine and the laboratory test. 

Regarding the conclusions from the parental acceptability focus groups, most parents would

agree to vaccinate if they have information on DENGVAXIA®. The most important barrier for 

parental consent to vaccinate with the dengue vaccine is lack of detailed information. The most 

important motivators are having information about the vaccine’s effectiveness; side effects; 

rationale for use in Puerto Rico; and current use in other countries; having the support of the 

UPR, PRDH, and CDC; and the disease prevention impact of the vaccine. The most important 

influencers will be pediatricians and the family.

Discussion Points

Dr. Romero inquired as to where the other 69% of vaccines are administered if only 31% of 

vaccines are administered in physician offices. 

Dr. Esquilin indicated that the other 69% are administered at either private or public vaccine 

administration clinics on the island. The vaccines that are provided by the VFC program are 

given to the patients in clinics that are run by the PRDH. The patients who have medical 

insurance can get their vaccines from private clinics established in various private hospitals on 

the island.

Dr. Szilagyi said he thought a lot of this confirmed other studies of providers and patients that 

there is general interest in vaccines, but that these practical feasibility issues can either facilitate 

or get in the way. He asked what the level of insurance coverage is for the laboratory test or for 

the vaccines beyond VFC in Puerto Rico, and whether the public health clinics perform the 

laboratory tests.
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Dr. Esquilin indicated that they do not have that information yet. They need to have the 

laboratory test approved and then submitted to the insurance companies to find out whether 

they will cover it. The laboratory test has to be done at a laboratory because in Puerto Rico, 

there are regulations that establish that physicians cannot do any laboratory testing in the office 

or in a clinic. It has to be done by a laboratory technician in the laboratory. They have not been 

able to do even HIV rapid tests in the labor room. There is no point-of-care testing in Puerto

Rico at this time.

Dr. Bernstein said it sounded like pediatricians would be a large influence on acceptance of this 

vaccine and providing the important information that is necessary, and asked whether in the 

health centers pediatricians or other child health professionals are administering the vaccine to 

69% of the children. If they are not going to see pediatricians, it will be difficult for pediatricians 

to be influencers. Plus, it adds additional steps to go to get the laboratory test and then the 

vaccination.

Dr. Esquilin responded that the pediatricians are not physically at the immunization clinics. They 

are depending on the information provided by the nurses on site. The pediatricians will see the 

patients in their offices and will recommend a vaccine, but most patients will still have to go to 

immunization clinics to get the vaccine. Then they will receive additional information from the 

nurses and the consent form from the administration clinic nurse. The pediatrician will 

recommend and order the laboratory test, receive the result, and approve the administration of 

the dengue vaccine.

Dr. Atmar pointed out that one of the issues the WG is struggling with, and ACIP also has 

struggled with during previous presentations, is the logistical nightmare of having to go through 

the additional step of getting the testing done. The child presents to the pediatrician’s office, 

then has to go to the laboratory to get the testing done, then the pediatrician has to evaluate the 

results, and then send the patient to the public health clinic to get the vaccine. While the vaccine 

may be a benefit to the child, the logistics of doing that and the additional concern of paying for 

the cost of the laboratory test, which is not covered through the VFC, is a problem. That is a 

major concern. One of the possibilities would be to get a point-of-care test, but it would require a 

change in the law essentially to allow that point-of-care test to be done in the doctor’s office—

assuming a sensitive and specific point-of-care test could even be developed.

Dr. Bernstein asked whether there is a reasonably robust electronic health record (EHR) if the 

difficulties with the hurricanes wiped out that option.

Dr. Esquilin indicated that for most of the hospitals and private pediatric offices on the island, 

there are no EHRs. In the main academic center in San Juan, an EHR was implemented about 

3 months ago. That is a major difficulty also for getting the results of the laboratory tests 

available. If an EHR is not available, patients will have to return to the pediatric office to deliver 

the results. It is difficult to determine past dengue infection because it must be filed in the paper 

medical record in the physician’s office.

Dr. Hunter said that as a clinician and as a medical advisory to a local health department, this 

analysis sets the standard for future similar analyses for the purposes of ACIP voting when 

there are such complicated implementation issues. The 3 study groups selected were very 

appropriate, the questions asked were right on track for what public health and clinical practice 

need to know, and the speed with which it was done and the size of the samples were 

appropriate for how fast this was needed. He commended Dr. Esquilin for setting the standard 

for the future.
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Dr. Lee asked whether there is an electronic immunization registry available and, if so, whether 

it would be possible to amend it to enable laboratory testing to be part of the record. She also 

inquired as to whether these children potentially would be eligible for the Vaccine Injury 

Compensation Program (VICP) if they experienced any adverse effects.

Dr. Esquilin indicated that they do have an electronic immunization record that was created 

through the VFC, which is available to the entire population, even from private clinics. They are 

going to work to change the registry to include the dengue vaccine and probably the laboratory 

result as well so that if a patient presents to a different clinic, they can easily find out whether 

the patient had the test done and qualifies to receive a first, second, or third dose of the vaccine.

Dr. Rubin (HRSA) responded that because Puerto Rico is a US territory, injuries alleged to be 

due to covered vaccines will be covered by the VICP. However, dengue vaccine is not covered 

at this time.

Dr. Goldman (ACP) observed that the study opened up a lot of possibilities, such as in South 

Florida. There is a very large population from Puerto Rico where he is in South Florida, so it 

would be interesting to expand this kind of work to determine whether there is any role for those 

who are not living in Puerto Rico and have moved to South Florida. Florida does have a registry, 

but the problem they have is implementation. While they do have electronic records, not 

everyone is fully integrated with the state registry. In terms of point-of-care testing, he has 

tested for dengue antibodies for patients of his who have traveled, had symptoms, and tested 

positive or negative. With the local and national laboratories, those tests can be done and the 

results communicated to the patients. It would be interesting to see some integration with the 

state vaccine registry and then be able to get the laboratory data.

Dr. Coyle (AIRA) pointed out that it is one thing to have an indicator indicating a positive or 

negative result, it is a different issue all together to incorporate laboratory results into an 

electronic immunization registry. Because of the considerations that need to be put in place and 

the interoperability between an EHH and an Immunization Information System (IIS), these are 

major shifts in the way this typically has been done. It is not impossible, but it does need to be 

considered.

Dr. Esquilin agreed that it is difficult, but expressed her hope that they can do it.

Dr. O’Leary (PIDS) recalled that 17% said they did not believe in vaccines and he wondered 

whether that level of vaccine confidence was common in Puerto Rico.

Dr. Esquilin responded that there is a high percentage of vaccination in Puerto Rico for most of 

the vaccines. What has helped significantly is incorporating vaccines as a requisite to enter 

school for school-aged children. The acceptability of vaccines on the island is actually very 

good. However, they do have groups who are against vaccines who are not willing to vaccinate 

their children.

Dr. Waterman clarified that the 17% represented 17% of those who did not want to use the 

vaccine. For the total surveyed population, it was much lower at about 3%.
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103

WHO Global Position on Dengue Vaccination

Joachim Hombach, PhD, MPH

Executive Secretary, SAGE

World Health Organization

Dr. Hombach spoke on WHO’s position and rationale on dengue vaccination, which has evolved 

and is important to understand. This vaccine has been used only in 2 very limited public 

programs, so the experience overall is not large. However, experience from other vaccines also 

can be drawn upon. WHO’s mandate is to advise countries on the use of vaccines against 

diseases of public health importance. The first generation dengue vaccine, DENGVAXIA®, was 

licensed initially at the end of 2015 and then in a number of endemic countries in 2016. In 2016, 

WHO issued its first position on dengue vaccination.

Dengue is really a global public health priority. In 2019, WHO had listed dengue among the 10 

biggest public health threats for the year. That was certainly done with the perspective that the 

environment is extremely favorable to further transmission and spread of dengue. This is 

combined with the situation that there are very few tools apart from environmental management 

and vector control, which is very difficult and very difficult to scale. The need for a vaccine is 

extremely important and unfortunately, the situation is that the vaccine is not very easy to 

implement. Dengue is not a high mortality disease if it is well-managed. Instead, it is a morbidity 

disease. It causes a lot of fear among populations, a lot of strain to the health system, and 

actually can have quite considerable economic costs. The survey just seen demonstrates that 

there is a high awareness around dengue.

In terms of the time scale of the 2 pivotal studies that were used for licensure of DENGVAXIA®, 

CYD-TDV 14 in Asia and CYD-TDV 15 in Latin America, had overlapping age groups. Asia was 

2 to 4 years of age and Latin America was 9 to 16 years of age. WHO’s position in 2016 took 

into account data that became available around Month 48. It is important to underline that the 

efficacy against symptomatic dengue was moderate, while the efficacy against hospitalized and 

severe dengue was actually very high. It is important to keep in mind that this vaccine has been 

performing very well against the more severe forms of the disease. The issue that occurred is 

that in the third year after the start of the trial, a safety signal occurred in the youngest group 

with an increase in hospitalized dengue. At that time, the evidence for what was causing this 

was not entirely conclusive. While there was a strong suspicion that it was tied and linked to 

serostatus, the way the trial was set up did not allow for a definitive conclusion of this.

A lot of supportive work was done through mathematical modeling for the first submission. WHO 

convened 8 mathematical modeling groups that essentially assessed the impact of the vaccine 

in different transmission settings. They way these models assumed that the vaccine would work 

was that essentially it was assumed that the vaccination acts like a primary silent infection, 

which then brings the person into a situation during which there is an increased susceptibility to 

the disease and secondary infection if they were naïve at the timepoint of the vaccination. 

Thereafter, the person should be in the secondary low disease risk base. If the person has 

already had a single infection, the vaccine to some extent would move it to the post-secondary 

phase where protection would be seen. This model structure fitted most nicely with the empiric 

data that was collected from the vaccine trial.
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WHO’s position in 2016 was essentially a position that was informed by trial data and 

extensively by mathematical modeling. It was a position of risk minimization in populations with 

a statement that basically, population-based recommendations should be done only if the 

seroprevalence of the entire population is high. The model predicts the highest effectiveness of 

the range of seroprevalence was about 70% at 9 years of age. There was a recommendation 

against using the vaccine in lower seroprevalence settings. When WHO issued the 

recommendation, they also issued a very strong call for the company or the global community to 

gather more data on the performance of the vaccine to understand the root causes of the safety 

signal and to be more specific in terms of risk minimization on the balance of risk when using 

this vaccine.

About 2 years later, the company performed an additional retrospective analysis. When they 

issued the first position, nobody actually knew that this was possible at that time to perform such 

an analysis that indirectly estimated the serostatus at baseline before the administration of the 

first dose. These data came out around Month 66. These were the data that resulted in a major 

outcry, particularly in the Philippines and other countries that started to use the vaccine in 2016. 

The study that was published in the New England Journal of Medicine (NEJM) used three 

different methods to assess serostatus at its baseline. It is important to understand whether the 

antibodies are actually derived from the vaccine, which has a Yellow Fever (YF) component, or 

from natural infection. Therefore, one approach involved testing a sample of vaccinees with a 

new dengue NS1 antibody test which is specific for antibody to wild dengue virus as opposed to 

vaccine induced antibody. Two independent statistical models also were used to impute the 

serostatus at baseline, and the results were pretty similar. Over the full duration of the 66 

months, the model shows continuous and reasonably robust protection against hospitalized and 

severe illness in seropositive individuals. However, the hazard ratio does not look favorable in 

the seronegatives. In other figures that include the younger age groups, this ration becomes 

even less favorable.

While that figure to some extent cooperated with what was in the mathematical models and also 

quantitatively very much fitted with the mathematical models, it created a major crisis in the 

sense that now there was a situation that they could describe and say which individuals would 

not benefit from the vaccine or would be put at risk. That also required WHO to reconsider its 

position, which they swiftly did. Risk minimization in seronegatives could still be thought of in 

terms of two approaches. One is still the population seroprevalence criteria without screening, 

perhaps with some tweaking in terms of what seroprevalence level would be accepted as the 

minimal level. The other is the individual-level pre-vaccination screening, which is the way the 

label has been changed. Both have major implications and come with major problems. A 

validated rapid diagnostic test for past infection is not available at this time, but there is a lot of 

work being done on this. When SAGE developed the policy, they considered a number of 

dimensions, including the following:

 Benefits and harm (population, individual, eligible populations)

 Ethical considerations (harm of omission versus harm of commission)

 Risk perceptions and communication (DENGVAXIA® crisis occurring in the Philippines)

 Screening tests versus serosurveys (feasibility, test limitations, costs)

 Implementation challenges

 Impact, age, cost-effectiveness

On balance, there was a very clear statement that this vaccine should be used only with 

individual-level pre-screening prior to vaccination, even though the door was left open 

somewhat for seroprevalence-based use of the vaccine.
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The WHO dengue position was updated on 7 September 2018 and is as follows:

Countries should consider introduction of the dengue vaccine CYD-TDV only if the minimization of 

risk among seronegative individuals can be assured;

For countries considering vaccination as part of their dengue control programme, pre-vaccination 

screening is the recommended strategy; 

Screening tests would need to be highly specific to avoid vaccinating truly seronegative persons 

and to have high sensitivity to ensure that a high proportion of seropositive persons are vaccinated.

Point-of-care tests, i.e. RDTs, would facilitate the implementation of the pre-vaccination screening 

strategy, but have not yet been validated for that purpose.

Decisions about implementing a pre-vaccination screening strategy with the currently available tests 

will require careful assessment at the country level, including consideration of the sensitivity and 

specificity of available tests.

The age group to target for vaccination depends on the dengue transmission intensity in a given 

country, and will be lower in countries with high transmission, and higher in countries with low 

transmission.

The optimal age group to be targeted is the age before which severe dengue disease incidence is 

highest;

If pre-vaccination screening is not feasible, vaccination without individual screening could be 

considered in areas with recent documentation of seroprevalence rates conducted at high

resolution;

Documented seroprevalence rates of at least 80% at age 9 years should be aimed at;

Communication needs to ensure appropriate and full disclosure of the risks of vaccination of 

persons with unknown serostatus (but also on false positives if prescreening with RDT is done).

The screening tests are a problem because high specificity is needed to avoid vaccinating 

seronegatives, but robust and high sensitivity also is needed to assure that the seropositives 

have really been vaccinated. Obviously, there is a lot of work that needs to be done and is going 

on in order to validate rapid diagnostic tests. The performance of the test depends upon the 

epidemiology of the setting, so it requires very careful assessment.

The age group for vaccination also is relatively tricky. It depends on the transmission intensity, 

as well as operation and programmatic considerations. From an epidemiological understanding 

of the vaccine performance point of view, the optimal age group is the one for which the most 

individuals have monotypic. That would be the age before the peak of severe disease as a 

proxy. The door was left open for a population-wide use of the vaccine with very high 

seroprevalence, even though this is not thought to be feasible. Most important is full disclosure 

and communication around the risks with this vaccine in relation to individuals with unknown 

serostatus, as well as communication around the risk that comes from false positives if prescreening with rapid diagnostic tests.
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There are a number of implementation considerations. It is very important to understand the 

local burden of disease and the age distribution to understand which group is best to target. The 

rapid diagnostic test must be assessed in the context of the specific epidemiological setting. It is 

clear that besides the vaccine, there will be the cost of the test and for the program operations. 

Program operations costs can be quite significant, which is known from other vaccines such as 

HPV delivered in schools. This is a relatively important cost factor that needs to be put into the 

equation. Implementation strategies depend upon the age group chosen, which might be of 

strong interest in school-based vaccination. It also is important to have the necessary follow-up 

and recordkeeping, including electronic records. There are communication issues as well. As for 

any vaccine, it is important to assess local priorities in relation to other alternative investments. 

It is extremely important to highlight that this is a vaccine that is partially effective, which means 

that vector control needs to continue and clinical management must be kept at a high level of 

support.

According to the way the vaccine works, the aim is to optimize and target the group that has the 

highest proportion of monotypic seroprevalence. This depends upon the force of infection and 

the transmission intensity. In higher transmission settings, the peak will be earlier and more 

distinct. There also will be less seronegatives, so even with the pre-screening approach there is 

more flexibility in terms of which transmission settings are targeted. It is certainly more effective 

and more cost-effective to go into settings with a pretty high burden of dengue.

The diagnostic tests are an area of active research. The positive predictive value (PPV) and 

negative predictive value (NPV) depend on the seroprevalence, so it is important to look at this 

in the context of the epidemiological setting. A group has conducted some surveys and 

interviews in Asia and Latin America in terms of acceptable level of sensitivity and specificity for 

rapid diagnostic tests. This is also something that needs to be brought into the equation if 

considering implementation of this vaccine.

Regarding communication, Heidi Larson surveyed the confidence in vaccines in general, 

vaccination in the Philippines, and after the dengue vaccine crisis. She found that a strong 

confidence in vaccine was completely shattered with the crisis, and now a very strong 

proportion of the population has a tendency to disagree with the importance and safety of the 

vaccine. This led to a decrease in vaccination coverage in general and provoked measles 

outbreaks, so the repercussions for an immunization program can be dramatic if the 

communications are not properly handled, as the Philippines situation has shown. The program 

in the Philippines was essentially abandoned after 800,000 doses had been administered. To 

Dr. Hombach’s knowledge, no follow-up evaluation is being done, so there were children who 

received either 1, 2 or 3 doses. Some of his colleagues did an estimation to try to understand 

the proportion of exceeding cases of dengue in relation to those being prevented through the 

use of the vaccine. This was based on the data from the Sanofi clinical trial, which had a large 

subgroup in the Philippines with the assumptions of seroprevalence and performance of the 

vaccine, it was estimated that about 18 dengue hospitalizations are avoided among seropositive 

for 1 precipitated hospitalization in dengue-naïve vaccinees and 10:1 in relation to disease. So, 

the overall performance of the vaccine is most likely to be positive, but it has not even been 

assessed and things have just been left in limbo, which is very unfortunate for the population 

and understanding of the vaccine.

In terms of communication, tailored and targeted communication is extremely important. 

Communication must be proactive—it must happen before a program is being put in place. 

WHO’s communication specialists tell them that once a perception has formed on a vaccine, it is 

very difficult to change it. It is very important to convey the facts and figures ahead of time. 
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Many things need to be communicated about this vaccine because it is very complicated. A 

recap of key communication topics for dengue includes:

 Clear communication on benefits and risks

 Rationale for pre-vaccination testing

 Risk of vaccinating seronegatives due to false-positive test

 Exclusion of tested persons from vaccination due to false-negative test

 Partial effectiveness of the vaccine and continued need for vector control measures

 Information on vaccine schedule

 Information on duration of immunity and possible needs for booster vaccination, which is 

still under investigation

Key considerations in developing a communication strategy are as follows: 

 Communication needs to be anticipated from the outset and must be proactive; avoid 

reactive communication

 The strategy needs to segment to different audiences (medical professional 

associations, general HCW’s, teachers, parents, adolescents, journalists...)

 Messaging and materials need to be targeted to different audience groups

 Communications is not enough—there needs to be opportunities for actual dialogue to 

build understanding and support.

In conclusion, dengue is a high public health priority in many countries. The current vaccine has 

shortcomings, but offers significant clinical benefit in a seropositive target population. Any use of 

the vaccine must be accompanied with a risk minimization strategy. Pre-vaccination screening 

is the method of choice to minimize risk. Vaccine performance is expected to be best in 

individuals with a history of monotypic infection. This population can most easily be targeted and 

identified in high-transmission settings. Rapid diagnostic test characteristics must be assessed 

in the context of the epidemiological setting. Significant investments are needed in relation to 

programmatic implementation, monitoring and communication. Failure to do so can have 

dramatic consequences for public health confidence. Surveillance, vector control, environmental 

management, and case management must be emphasized in the dengue endemic setting, 

irrespective of whether a vaccination program is implemented.

Discussion Points

Dr. Poehling requested clarity about whether the estimations on Slide 18 were for the entire 

population, and whether they have separated the estimation of those preventions to those 

precipitated by age group for the children 9 to 16 years of age in particular.

Dr. Hombach said the assumption here regarded whether the vaccine performs the same if 1, 2, 

or 3 doses are given. Because this is not known, they had to assume.

Dr. Lee found it incredibly helpful to hear WHO’s experience and what went into their decisions. 

She found it interesting because she was realizing that in a way, the way this was framed is the 

way value in healthcare in general is thought of. One of the things in addition to considering 

population benefits/risks and individual benefits/risks is that the way WHO evaluated the impact 

of its recommendation and subsequent implementation also takes into consideration the impact 

on providers and patients. She was particularly struck by the vaccine confidence slide, which 

was interesting and offered a good way for ACIP to think about the impact of its 
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recommendations in that how they make them and how they communicate them can make a 

major difference in public health efforts to help the population.

Summary of WG Considerations

Steve Waterman, MD, MPH

Chief, Dengue Branch 

Centers for Disease Control and Prevention 

San Juan, Puerto Rico

Dr. Waterman summarized the Dengue Vaccines WG’s latest considerations. As Dr. Atmar 

mentioned, the WG does not expect to make recommendations until an independent evaluation 

of the specificity of available laboratory screening tests for past dengue infection is available for 

presentation to ACIP. This contingency makes it likely that the WG would not make a 

preliminary recommendation until the October 2020 ACIP meeting at the earliest.

First, Dr. Waterman summarized what he thought the WG considered the key points and takehomes from Dr. Esquilin’s presentation on community, pediatrician, and parent knowledge and 

sentiments about DENGVAXIA® in Puerto Rico. The key survey results showed that 73% of 

pediatricians would use DENGVAXIA® given an acceptable pre-vaccination screening laboratory 

test. The majority (84%) of pediatricians would like to see a screening test with a specificity of at 

least 95% and preferably 99%. About 76% of pediatricians supported a pilot project. Over 80% 

of pediatricians felt the vaccine and laboratory test insurance coverage were necessary steps 

for implementation. Clearly, parents and physicians need more education about the vaccine. 

There is a need to explain the rationale for vaccinating in dengue endemic areas such as Puerto 

Rico. There were relatively few negative perceptions about the vaccine in the surveys that were 

conducted.

The Dengue Vaccines WG conducted an informal poll of its formal members last December.

The WG members were asked to comment on what information is needed to make a 

recommendation on DENGVAXIA®. By far, the biggest and most often mentioned concern was 

having an acceptably specific pre-vaccination screening laboratory test for past dengue 

infection, and the sense that there is not yet enough information about available tests. The 

logistical challenges of pre-vaccination screening and the cost of the laboratory test also were 

frequently mentioned. Dr. Hombach’s presentation echoes the WG’s concerns about unintended 

consequences and the importance of community engagement to assure the perception of 

transparency. A number of WG members felt that a pilot vaccination program could be 

implemented in children with documentation of previous dengue infection in the medical record, 

and Dr. Esquilin’s presentation on the Puerto Rico survey suggests support for such an 

approach among Puerto Rico pediatricians. A pilot vaccination program might enable logistical 

issues to be worked on and solved. With regard to a pilot, one WG member commented that an 

anticipatory recommendation would allow for insurance coverage for the laboratory test to be 

put in place as testing technology improves, and argued for the advantage of having a 

recommendation in place in advance of possible dengue outbreaks. A number of WG members 

expressed skepticism about a shared decision-making recommendation. Comments included 

that shared decision-making passes off the decision making to the clinician, and that such 

decision-making would be complex and could depend on the level of education of the family.
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The CDC Dengue Branch Laboratory is in the process of evaluating available and newly 

developed dengue IgG laboratory tests. The process involves three steps, the first of which is 

the WHO and CDC landscape analysis that has been mentioned previously. As a result of that 

first step, 14 laboratory tests will be evaluated. CDC has recently procured a number of these 

tests and is in the process of procuring the others. Two stages of evaluation are planned, with 

the first being evaluation for the intended use of many of these tests for diagnosis of acute 

dengue infection, and the second evaluation based upon performance of long-term samples for 

past infection. All of the tests will be evaluated head-to-head with a curated set of PCR-positive 

samples CDC has selected, with the hope of completion of the process by the next ACIP 

meeting.

As a reminder, Dr. Perkins presented data from the University of Notre Dame’s modeling of the 

cost-effectiveness of DENGVAXIA® in Puerto Rico during the October 2020 ACIP meeting, but 

did not have an opportunity to share these tables at that time:

Baseline Baseline Averted Averted

Prior 

Exposure 

in 9 Year 

Olds

Symptomatic Hospitalizations Symptomatic Hospitalizations

Additional 

Hospitalizations

0.3 225,460 51,790 1,886 1,662 214

0.5 262,852 62,113 4,652 3,415 184

0.6 275,317 64,571 6,377 4,664 164

The table provides the estimated population impact of DENGVAXIA® vaccination in Puerto Rico 

over a 10-year timeframe for vaccinating 9-year-olds screened by a laboratory test with 95% 

specificity and 80% sensitivity at different seroprevalence levels. With a 50% dengue 

seroprevalence, which is what preliminary data show for Ponce, Puerto Rico, about 3400 

hospitalizations would be averted among seropositives, and 184 additional hospitalizations 

would be seen among vaccinated dengue naïves who tested seropositive—a ratio of over 

18.6:1.

Regarding one of the questions raised about where laboratory testing would be performed in 

Puerto Rico, Dr. Waterman indicated that there are currently 2 laboratory tests that are Clinical 

Laboratory Improvement Amendments (CLIA-approved) that Sanofi has evaluated in 

publications. Their evaluation showed 99% specificity. These tests are available at private 

laboratories. There have been discussions with the health department regarding whether they 

could perform these tests, but that is completely up in the air. 

In conclusion, Dr. Waterman invited feedback on whether there were other specific data ACIP 

would like to see and/or other considerations ACIP would like the WG to address.

Discussion Questions

Dr. Wharton asked if the primary side effect of concern is severe dengue, that hopefully most 

patients would fully recover from without sequelae, whether that would be covered by the VICP. 

While she understood that dengue vaccine is not covered at this time, if it were recommended 

and the vaccine was included in the VFC program, she thought that the program was designed 
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110

to address adverse events that have long-term sequelae rather than something like an illness 

that might result in hospitalization from which the patient would recover.

Dr. Rubin (HRSA) responded that there is a severity requirement. In terms of being eligible for 

compensation, symptoms have to last more than 6 months or there should be inpatient 

hospitalization for intervention or death.

Dr. Poehling asked if VICP coverage would be impacted by whether the recommendation is for 

shared decision-making versus being fully recommended.

Dr. Rubin (HRSA) replied that what is currently covered in the VICP program are vaccines that 

ACIP has routinely recommended for children that are in the immunization tables, not 

necessarily clinical decision-making.

Dr. Cohn said she thought it was similar to VFC and private insurance coverage in that, if it is on 

the immunization schedule, it will be included in the VICP. It can be either routine in that all 

children in a group should receive a vaccine or children should receive a vaccine based on 

shared clinical decision-making. This is in general how this has been done.

Dr. Rubin (HRSA) added that for example, meningitis is covered for age groups versus specific 

populations at this time. To be covered, ACIP has to recommend a vaccine for routine 

administration to children, but there also are other procedures before the coverage goes 

through.

Dr. Lee emphasized the importance of being mindful of potential disparities in access to testing 

or care that may result, and that her question derives from the fact that she is worried about 

families who may not have the ability to pay for hospitalizations out-of-pocket if that were the 

case and/or other sequelae.

Dr. Waterman said he thought Dr. Esquilin would be in the best position to answer that question, 

but his impression was that access to care in Puerto Rico is quite good. A large percentage of 

the population is covered by the indigent healthcare system. While the healthcare system has 

been compromised by the public debt, overall access is good in general. He believes that 

children who have severe illness have access to hospitalization. Dr. Esquilin concurred with Dr 

Waterman’s response.

Dr. Szilagyi said he was intrigued by the concept of a pilot project. Often in system or practice 

improvement, a pilot is conducted to work out feasibility issues. He wondered what the goal 

would be for the pilot and what would be learned that then would allow it to be scaled up in a 

meaningful way.

Dr. Waterman stressed that this is a complex logistical process to undertake. Most of the

discussions regarding pilots is that there is not a large population, but a significant number of 

persons who already have documented dengue infection in their medical record and that they 

could start to vaccinate those persons. Simultaneously the education process could continue 

along with work to resolve some of the logistical and insurance issues that have been raised. 

The argument could be made that this would be a symbolic gesture that might not have much 

population impact, but it would get some children vaccinated and perhaps could generate 

momentum toward figuring out how to make this a programmatic process if that was the will of 

the health department and the pediatric community. It would not be a pilot of the 2- or 3-step 

laboratory process, though that might be piloted eventually as well.
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Dr. Cohn asked whether the WG had discussed whether an ACIP recommendation would be 

needed for the specific group of individuals who have documented previous dengue before 

conducting a pilot, from an economic perspective.

Dr. Waterman responded that they had not done so from an economic perspective. While there 

is individual benefit to the vaccine, the WG would want to see some type of ACIP 

recommendation before commencing a pilot. Further discussion is needed on that.

Dr. Atmar added that the WG has not specifically addressed that, but the discussions thus far 

have been in the context of an ACIP recommendation. Part of the rationale for that pertains to 

covering the cost of the vaccine, which potentially is a major consideration.

Dr. Maldonado (AAP) said she thought they had come a long way since the original discussions. 

She does want to revisit the issue of a pilot at some point and what that actually means, given 

that there are complex scientific, functional, and operational issues. It would be helpful to try to 

pilot the building of a screening test into public and private sector settings. There will be a series 

of steps depending upon the sensitivity/specificity of the test, informed consent, who will pay, et 

cetera. A pilot may be beneficial in helping to answer some of these complicated issues. For 

example, rapid testing was rolled out for HIV through a series of implementation demonstration 

projects in the US. It took a while to acquire community input, engaging healthcare personnel, et 

cetera. It took a while to get that all aligned before legislation could take place. Now it is 

generally seamless, but it took a lot of work to get there.

Dr. Waterman emphasized that consent is a very important issue. While it may not be informed 

consent as in a clinical trial, behavioral scientists will need to develop culturally appropriate 

language to ensure that the community understands the risks and benefits and have that 

thoroughly researched ahead of time. Even for a pilot, there would need to be considerable 

education of physicians in the community.

Dr. Hunter thinks one of the major advantages of conducting a pilot would be increasing the 

confidence of the general public, pediatricians, and parents that they will be heard and 

implementation will be done correctly. If he were in Puerto Rico in the local or territorial health 

department, he would want to be the ones deciding whether a pilot would be conducted. While 

he would consider CDC guidance, a pilot would need to be implemented by the local folks with a 

lot of support. Therefore, they should have the authority to do that.

Dr. Waterman responded that the PRDH is the spokesperson for immunizations in Puerto Rico, 

so that clearly would have to occur.

Dr. Atmar said that his understanding of the way that the childhood immunization program has 

worked in Puerto Rico, particularly with respect to the high compliance because of the school 

requirements, one of the challenges with shared decision-making would be that if dengue 

vaccine was added to the schedule, it would be handled like other childhood vaccinations 

assuming a child is seropositive. While there would be information presented to the family, 

whether it would be required as part of attending school to increase compliance and make the 

system work has not been fully decided. That would be the usual means by which such 

vaccinations would be implemented. There was some concern in the WG that this could cause 

problems in the future.
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Introductions

Tom Shimabukuro, MD, MPH, MBA

Immunization Safety Office

Centers for Disease Control and Prevention (CDC)

Dr. Shimabukuro indicated that during this session, Dr. Walt Ornstein would provide a historical 

perspective on the US transition from oral polio vaccine (OPV) to the all inactivated polio 

vaccine (IPV) schedule. Dr. Ornstein is with Emory University and was the Director of CDC’s 

National Immunization Program (NIP) during the switch. Dr. Ornstein would be followed by Mr. 

John Salamone, a former consumer representative member of the ACIP and former member of 

the Advisory Commission on Childhood Vaccines (ACCV). Mr. Salamone was accompanied by 

his wife, Kathy. Their son, David, contracted vaccine-associated paralytic polio (VAPP) from an 

OPV vaccine he received as a child. The Salamones’ public advocacy for switching to an all-IPV 

schedule was a key factor in accelerating the change. Mr. Salamone would be followed by, Dr. 

Stephen Cochi from CDC’s Global Immunization Division (GID) who would provide an update 

on progress and prospects for global polio eradication.

Polio and Polio Policy in the US: The OPV to IPV Switch

Walter A. Orenstein, MD

Professor of Medicine, Global Health, Pediatrics, and Epidemiology

Emory University 

Dr. Ornstein indicated that it had been 20 years since the US embarked on an all-IPV schedule 

in 2000. It was a difficult decision to abandon OPV because of fears that there could be polio 

outbreaks. The fact that OPV crippled people for life when there was a perfectly safe alternative 

IPV, led to the decision to move to an all-IPV schedule. There was medical consensus that this 

was causally related, albeit very rare. Dr. Ornstein said that his goal for this session was to 

explain why the decision was difficult and what led to making the decision to move to an all-IPV 

schedule, which he discussed in the context of three eras.

Polio vaccination began with IPV in 1955. In 1961, there was a switch to OPV that lasted until 

1997 when a sequential schedule of IPV followed by OPV was adopted. The present era of IPV 

has spanned from 2000 to the present. This is a graph of polio in the US. It is important to note 

that this is a log scale and should be interpreted with caution:

Polio Informational Session
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In 1961, the US went to an all OPV schedule administered at 2 months, 4 months, 6-18 months, 

and 4-6 years. The sequential schedule that began in 1997 included 2 doses of IPV at 2 and 4 

months and then 2 doses of OPV to get the benefits of both vaccines. That was followed in 

2000 by the 4 IPV doses administered at 2 months, 4 months, 6-18 months, and 4-6 years. 

There was a marked reduction in polio with IPV, but some problems were still being observed 

with it at that time. Switching to OPV, there was a marked reduction. The last outbreak of polio 

in the US was in 1979. While there was no wild polio virus (WPV) after that, there still were 

about 8 to 10 cases a year of VAPP. The switch to sequential resulted in a reduction of cases, 

but did not eliminate poliovirus. Subsequent to the switch to all-IPV, there has been no polio.

The OPV era lasted from 1961-1997, Albert Sabin pioneered the live-attenuated weakened 

viruses. These were preferred for a variety of reasons. First, it was substantially less expensive 

than the IPV. In addition, it was substantially easier to administer. Non-technical individuals 

could be trained to administer it because it was oral as opposed to requiring injections. A major 

issue was that it was far better at inducing intestinal immunity than IPV. IPV and OPV both 

induced great individual systemic immunity, so they protected the central nervous system 

(CNS). However, IPV could be inferior in terms of the intestinal side and the extent that fecaloral spread was important or not. Another advantage of the OPV at the time, before the 

detection of circulating vaccine-derived poliovirus (VDPV), was that passive spread of the 

vaccine viruses permitted immunization of individuals who were not being reached in the 

immunization program who would have been completely susceptible with a switch to IPV.

Roland Sutter assembled some data pertaining to intestinal immunity and shedding in two 

studies. One study was by Ghendon and Sanakoyeva many years ago in which he studied 4 

groups of patients: Susceptible Control Subjects, IPV-Vaccinated, OPV-Vaccinated, and 

Naturally Immune. He challenged them with a Type 1 oral vaccine virus and then assessed the 

proportion of shedding, the duration, and the mean titer of virus excreted to calculate an 

excretion index. With regard to fecal shedding, the IPV group was not very different from the 

OPV group. They shed for a somewhat shorter period, but substantially more than the OPV 

group and at a substantial 2-log increase titer and about a 1-log difference from the completely 

susceptible individuals. IPV was 95% better than nothing, but 5 times worse than OPV.
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At that time, it was unclear what that meant. The other data are from Onorato and McBean 

looking at children who received a complete schedule of IPV or a complete schedule of OPV 

and then were challenged with 2 doses of OPV. With regard to oral transmission, which would 

be dependent upon a pharyngeal setting, there was no real difference in IPV or OPV. They were 

equivalent. Where IPV was clearly inferior was in intestinal shedding. One of the issues that was 

not clear was the major mode of transmission in the US at the time.

The other advantage of the oral vaccine regards the spread. Chen and others led a study in 

1996 of children in Detroit and Houston who were documented to be completely unvaccinated. 

High proportions of them were found to have antibody to polio, suggesting that passive spread 

of the oral vaccine virus was good because it was reaching people who were not being reached 

by the program. At this point, nothing was known about circulating VDPV polio outbreaks.

In 1960 when the switch was made from IPV to OPV, there were still between 2500 and 3000 

cases still occurring. Even though there was IPV at that time, it was not as potent as the current 

IPV. After the switch, there was a dramatic reduction, but there remained a constant level of 

polio occurring. One of the things that made everyone feel better, but in retrospect was not 

adequate was that there was a Vaccine Injury Compensation Program (VICP). For the 8 to 10 

people who were paralyzed a year due to the OPV, at least there was financial renumeration 

that began in October 1988. It applied not only to recipients, but also to passive contacts of 

recipients who developed VAPP.

Moving to the sequential schedule era that began in 1997, the doses of IPV were administered 

at 2 and 4 months and the age was raised for the third dose at that time to 12 months. That was 

in part because one of the major risk groups for paralytic polio from OPV were those with 

immune deficiencies. Waiting to administer the OPV gave more time to diagnose those immune 

deficiencies. The hope was to achieve the benefits of both vaccines. Overall, there was about 

one case of VAPP per about 2 million doses of trivalent OPV (tOPV) distributed. The risk was 

highest after the first dose at 1 per 750,000 doses compared to subsequent doses at 1 per 5.1 

million doses. The case categories included: Recipients, Contacts, Community-Acquired, and 

Immunologically Abnormal. The immunologically abnormal group was large, particularly those 

with B-cell immunity defects. As this period occurred, less and less risk was observed of wild 

virus. This called into question continued use of this vaccine, given the lower risk.

The Americas were certified as being WPV-free in 1994, with the last case occurring in Peru in 

1991. In a meeting in June 1996, parents and children with VAPP attended the ACIP meeting 

and had a major impact on the thinking. Dr. Ornstein read a passage from the ACIP minutes 

that were recorded at the time, “They described the parents’ emotional and financial burdens, 

though significant, as inconsequential compared to their children’s probable lifelong struggle to 

have a normal life. Repeatedly, they stressed that these tragedies need not have happened. 

They agreed that OPV’s risk was not adequately conveyed.” This was not about polio vaccine 

versus no vaccine, but instead was about a polio vaccine versus a polio vaccine and one which 

was completely safe. This was very different from having only OPV, in which case OPV use 

would have continued.

The reasons for adopting a sequential schedule were that: 1) a sequential schedule was 

expected to reduce recipient VAPP by more than 90%; 2) a sequential schedule may reduce 

contact VAPP; 3) continued use of OPV induces high levels of intestinal immunity; 4) 

maintaining OPV in the schedule results in fewer injections than going to an all-IPV schedule; 5) 

and stocking of both vaccines facilitates choice for providers. The ACIP recommendation 

published in the Morbidity and Mortality Weekly Report (MMWR) on January 24, 1997 read:
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“ACIP recommends a transition policy that will increase use of IPV and decrease use of 

OPV during the next 3–5 years.”

 “...The risk-benefit ratio associated with the exclusive use of OPV for routine 

immunization has changed because of rapid progress in global polio eradication 

efforts.” 

 “The relative benefits of OPV to the U.S. population have diminished because of 

the elimination of wild-virus–associated poliomyelitis in the Western Hemisphere 

and the reduced threat of poliovirus importation into the United States.” 

 “The risk for vaccine-associated poliomyelitis caused by OPV is now judged less 

acceptable because of the diminished risk for wild-virus–associated disease 

(indigenous or imported).” 

This is the summary table depicting the advantages and disadvantages of the three vaccination 

options:

A very important study was conducted by Mark Miller, who was at CDC at the time, taking into 

account the higher costs of IPV showing that changing to an IPV-only or a sequential schedule 

would cost $28.1 million and $14.7 million, respectively. The bottom line is that the costs per 

case of VAPP prevented were estimated as $3.0 million and $3.1 million for each option, 

respectively. Despite that, the need was felt to switch due to moral and ethical reasons.

Moving to the IPV-only era, Dr. Ornstein called out Dr. Paul Offit, who played a major role 

having chaired the ACIP WG on Polio during this period that led to the all-IPV recommendation. 

With the change to a sequential schedule, VAPP was reduced but was not eliminated. It was not 

that the IPV failed, but was the fact that many providers having OPV in their stock were still 

administering OPV first without IPV. Therefore, the problem was still occurring with the 

sequential schedule. During 1997-1999, 13 VAPP cases occurred, 7 in 1997 and 3 each in 1998 

and 1999. None of these cases occurred in persons who had followed the sequential IPV-OPV 

or all-IPV schedules. Of the cases, 9 occurred in OPV recipients, 6 of which were associated 

with a first OPV dose; 2 occurred among contacts of OPV recipients who had not followed the 
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sequential schedule; and 2 were among immunologically abnormal OPV recipients, both 

associated with a second dose. There have been no cases of polio since 2000.

In terms of key issues, continued VAPP cases were seen. There were no declines in childhood 

immunization coverage seen after adoption of the sequential schedule. No indigenous WPV 

has been seen in the US since 1979. Further progress was made by the Global Polio 

Eradication Initiative (GPEI) toward eradication (i.e., decreased risk of importation). No declines 

in immunization coverage were observed, despite the need for additional injections. 1

CDC 

investigated the impact of the change to a sequential IPV-OPV vaccination schedule at two 

large West coast health maintenance organizations (HMOs), which found that children receiving 

IPV as their first polio vaccination were as likely to be up-to-date at age 12 months as children 

receiving OPV. 2

CDC's National Immunization Survey (NIS) provides ongoing estimates of 

vaccination coverage in the United States. National vaccination coverage achieved was greater

than or equal to 90% each for three doses of poliovirus vaccine [1

Impact of the Sequential 

IPV/OPV Schedule on Vaccination Coverage Levels -- United States, 1997 [Internet]. [cited 

2017 Jan 4]. Available from: https://www.cdc.gov/mmwr/preview/mmwrhtml/00055785.htm

2

Centers for Disease Control and Prevention (CDC). National vaccination coverage levels 

among children aged 19-35 months--United States, 1998. MMWR Morb Mortal Wkly Rep. 1999 

Sep 24;48(37):829–30].

In June 1999, the ACIP recommended an all-IPV schedule:

“ACIP recommends an all-IPV schedule for routine childhood polio vaccination in the 

United States to eliminate the risk for VAPP.”

 “Since 1997, the global polio eradication initiative has progressed rapidly, and the 

likelihood of poliovirus importation into the United States has decreased 

substantially.”

 “The sequential schedule has been well accepted, and no declines in childhood 

immunization coverage have been observed.”

Regarding the take-home messages, science is critical in making recommendations. There 

were unknowns and it is difficult because decisions must be made without all of the information 

sometimes. Epidemiologic and implementation science alone are not the only inputs into policy. 

Moral and ethical issues need to be considered. Cost-effectiveness can be superseded. Had the 

concerns about the lack of intestinal immunity and decreased coverage with IPV turned out to 

be correct, ACIP would have been severely criticized. However, it was necessary to make that 

decision based on what was known and this was the most appropriate decision. It has turned 

out to be the right decision as there has been no polio in the US since 2000.

Discussion Points

Dr. Hunter emphasized that this is a great example of what history can teach us, and it 

demonstrates how ACIP needs to balance difficult issues, safety, and other issues with the need 

to make a decision in the absence of all of the information.

Dr. Kimberlin (AAP) recalled that there was perhaps an enhanced IPV product and wondered 

when that was developed and how it factored in with the decision-making, and whether the 

sequential approach was an option from the beginning and who thought of it.
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Dr. Ornstein indicated that the enhanced IPV was licensed in the 1980s. It did play a role 

because in essence, the IPV used in the 1950s was not as potent and not as immunogenic as 

that IPV. The enhanced potency IPV was the only vaccine at the time these decisions were 

undertaken. Regarding the sequential approach, he thought the initial debate was one or the 

other. The sequential approach consideration regarded the notion of getting the benefits of both 

of the vaccines. There were data from Hungary in which IPV preceding OPV caused a major 

reduction in VAPP. The sequential approach was a “no lose” option until they found out that you 

did lose. It was thought to be the best schedule to begin with and clearly, there were no cases of 

VAPP between 1997 and 2000 in people who had received the sequential schedule.

Dr. Romero observed that presentations such as this allow ACIP to look back at the efforts the 

committee has made and allows them to focus past efforts on current problems and projects.

Parent/First ACIP Consumer Representative

Mr. John Salamone

Past Consumer Representative, CDC Advisory Committee on Immunization Practices 

Past Member, HHS Advisory Commission on Childhood Vaccines

Mr. Salamone expressed his gratitude for the opportunity to appear before ACIP. He noted that 

it had been 17 years since he served on ACIP, and that it was nice to be back among familiar 

and friendly faces. He found himself thrust into the polio vaccine debate because his son, David, 

was born with Bruton’s Disease Syndrome, an immunodeficiency disorder that prevented him 

from making B-cells. Because of that genetic disorder, David, like dozens of other US children 

at the time, contracted polio from the oral vaccine as an infant in 1990. It left him with an 

atrophied leg, but with the help of physical therapy, a brace, and a supportive family, he lived a 

somewhat normal life.

After dealing with the initial grief of seeing their only son disabled, he and his wife Kathy were

determined to find out why a seemingly healthy baby would suddenly lose the use of his leg

overnight. They discovered that other children experienced similar adverse reactions each year 

from OPV, even though there was a safer and just as effective IPV. While removing an

entrenched vaccine from the market that had been a mainstay in immunization history for 40 

years was not easy, it had to be done. OPV did its job and did it well, but any vaccine needs to 

undergo a periodic benefit/risk evaluation. In the case of OPV, the only cases of polio in the US 

for decades stemmed from the very vaccine meant to eliminate the disease. Changing to a safer 

IPV schedule was critical and overdue. 

With his background in journalism, Mr. Salamone knew he could write—so that was what he did. 

He reached out to magazines, newspapers, and broadcast media to tell David’s story and the 

need for a safer all-IPV immunization schedule to replace the current all-OPV schedule. To his

surprise, he started to get calls and stories on David began to appear in newspapers like the 

Washington Post and the New York Times, as well as magazines such as Good Housekeeping

and Family Circle. Since he had worked in Congress in the 1970s, he contacted some old 

friends, and even the White House since President Clinton’s Chief of Staff, Leon Panetta, was a 

friend for 20 years.

They felt that they were getting out the world, but nothing was changing. They desperately 

wanted a safer polio vaccine, but they knew they could not get it with just press and politicians. 

They made their case to the media and Congress, and now they needed to focus on the

decision-makers and work within the system at the CDC. It was time to go to Atlanta. Mr. 
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Salamone researched and discovered other VAPP families throughout the US. They shared 

their stories and their pain. He convinced many of them to join him and Kathy at a meeting of 

the ACIP in June 1996 in a room much smaller than the one in the Global Communication 

Center (GCC) and located in another building. This was clearly a turning point. He thinks they 

spoke to the hearts and minds of ACIP members who, for the first time, saw the faces and 

braces of those behind the statistics. It helped those children, and especially his David, feel they 

could make a difference and help others. Their sacrifice was not in vein. While it took several 

more years, ACIP transitioned to an all-IPV schedule in 2000. Since that date, there have been

no cases of VAPP in the US. The US can now truly be said say that since the year 2000, polio 

has been eradicated in the US. 

In conclusion, Mr. Salamone said that he learned several things from this experience. He 

learned that the professionals who work at the CDC and who serve on important committees

like ACIP are dedicated, intelligent, caring individuals who take seriously their responsibility to 

create a world where people are not injured and die from preventable diseases. Because of 

their work, many of those diseases such as smallpox, measles, rubella, tetanus, diphtheria, and 

polio have been virtually eradicated in the US. Today, the CDC and ACIP are on the frontlines 

of protecting Americans from the growing concern of coronavirus. They have saved too many 

lives to count, and he expressed gratitude to them for the decisions they have made based on 

science and not rumors and unwarranted fears.

Mr. Salamone said he wished David were there on the 20th year since VAPP-free America. He 

passed away on September 7, 2018. On his last ambulance ride to Georgetown Hospital, he 

said to his mom, “I wanted to do something good for people. I know I could help.” David did 

good and he helped. He and Kathy are grateful that CDC and ACIP recognized his contributions 

and those of others for a safer US immunization program.

Dr. Shimabukuro requested that Kathy Salamone and Dr. Ornstein join him and John Salamone

on the stage. Through the generosity of the CDC Foundation, Dr. Shimabukuro presented the 

following plaque honoring David Salamone, his parents John and Kathy, and other families who 

advocated for switching from OPV to IPV. Immediately following this session, the plaque was to 

go on display in front of the CDC library:
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Dr. Romero pointed out that Mr. Salamone was the first Consumer Representative on the ACIP. 

His work continues today through each subsequent generation of Consumer Representatives 

ACIP has. He has a living legacy on this committee.

Global Polio Eradication: Progress and Prospects

Stephen L. Cochi, MD

Senior Advisor to the Director

Global Immunization Division, Center for Global Health

Centers for Disease Control and Prevention

Dr. Cochi provided an update on global polio eradication and the effort to eliminate all poliovirus 

disease, WPV and VAPP, pointing out that he had good and bad news to share. The four 

primary strategies being followed in the polio eradication and endgame strategy include:

1. Poliovirus Detection and Interruption

2. OPV2 Withdrawal, IPV Introduction, Immunization System Strengthening

3. Containment and Global Certification

4. Transition Planning

During this session, Dr. Cochi focused on Strategy 1—poliovirus detection and interruption. 

Before the Global Polio Eradication Initiative (GPEI) began, polio was endemic in 125 countries 

and paralyzed over 350,000 children every year. As of the end of 2019, there were only 3 polioendemic countries: Afghanistan, Nigeria, and Pakistan. While Nigeria is still considered to be an 

endemic country, it has not had WPV in over 3 years and soon may come off of the list of 

endemic countries. In terms of major milestones, the last WPV Type 2 (WPV2) occurred in India 

in 1999. India had the last WPV case in 2011, which was a major milestone in the world. In 

2015, the Global Certification Commission (GCC) formally certified the world as free of WPV2. 

The same occurred for WPV Type 3 (WPV3) in 2019. WPV3 has not been seen anywhere in the 

world since 2012 in Nigeria. Given the accelerated global effort, since 1988 the number of polio 

cases averted on an annual basis globally has increased tremendously. Cumulatively, nearly 19 

million polio cases have been prevented in the world through polio vaccination. The certificate 

showing that the world is free of WPV3 was signed on October 17, 2019 by the GCC headed by 

Professor David Salisbury of Great Britain.

To summarize the good news, more than 7 years have passed without detection of WPV3. The 

GCC certified WPV3 eradication last Fall. The number of inaccessible children in formerly Boko 

Haram-controlled areas in Borno State, Nigeria has been drastically reduced from about 

500,000 children inaccessible in 2016 to a current estimate of about 30,000 children who remain 

inaccessible. These estimates are determined by satellite photography that is done on a regular 

basis to look at villages and towns that are still in existence or have been burned or otherwise 

destroyed by Boko Haram. More than 3 years have passed without detection of any WPV in 

Africa. The African RCC will convene in June 2020 in Nigeria on a preliminary basis to 

determine regional certification of all WPV disappearance in the African Region. IPV supplies 

are now sufficient for routine immunization, and catch-up of missed cohorts is in progress. 

There was a major problem with the supply when IPV was added to OPV-only using countries. 

There is a cohort of about 40 million children who need to be caught up since 2016. The Europe 

Regional Office (EURO), Pan American Health Organization (PAHO), and South East Asia 

Regional Office (SEARO) of WHO all remain polio-free, including from circulating vaccinederived poliovirus type 2 (cVDPV2). Gavi (the Vaccine Alliance) has joined GPEI. 
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Now for the bad news. This is a graphic of the WPV1 and cVDPV cases for the previous 6 

Months in the world as of February 18, 2020:

The red dots represent cases if WPV1 is limited to Afghanistan and Pakistan, with the bulk of 

cases occurring in Pakistan. The green dots reflect cases of cVDPV2, while the small number of 

yellow dots represent an outbreak of cVDPV1 in Malaysia and the Philippines.

To summarize the bad news, WPV1 cases increased from 33 cases in 2018 to 173 cases in 

2019. Of those, 144 were in Pakistan where there was a major surge in polio cases. The 

Taliban ban on house-to-house vaccination in Afghanistan is severely affecting the ability of the 

program to carry out campaigns. In Pakistan, a new government is starting to provide national 

leadership. However, over 6 months passed in the second half of 2019 without large-scale 

vaccination campaigns and WPV cases surged. WHO’s Africa Regional Office (AFRO), Eastern 

Mediterranean Region Office (EMRO), and Western Pacific Regional Office (WPRO) all battle 

outbreaks of cVDPV2. 

To further explain cVDPV, polioviruses can rarely regain the ability to cause paralysis and tOPV

has attenuated WPVs. That attenuation results in markedly less ability to cause paralysis than 

WPV, less capacity to pass from person-to-person than WPV, and a similar induction of 

antibodies as WPV. OPV polioviruses in areas with low polio vaccine coverage can rarely 

mutate during prolonged circulation and become VDPVs. That mutation consists of backmutations to make the vaccine neurovirulent, as well as recombination events with non-polio 

enteroviruses (EVs) to make the vaccine viruses better able to transmit and cause paralysis. 

These viruses become VDPVs, which is the scientific name given to these viruses. They are 

able to spread and cause paralysis and outbreaks rather than just isolated cases of VIPP. 

Those viruses are the result of back-mutations toward neurovirulence.
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Approximately 700 paralytic cases cVPDV2 polioviruses cases were confirmed during the 15-

year period from 2001-2015, while there were no WPV in the world. This prompted the strategic 

decision to withdraw OPV2 use in all routine and supplementary immunization activities going 

from a trivalent to a bivalent 1 and 3 serotype vaccine. In 2016, the policy was implemented to 

remove the Type 2 component and go to a bivalent vaccine in 155 OPV-using countries in the 

world. This switch took place over the course of about 1 month. This was a massive effort 

because it involved taking back and destroying every vial of tOPV, ceasing further distribution of 

this vaccine, and adding IPV in order to benefit from both vaccines.

The rationale for introducing IPV was that IPV complements tOPV by increasing immunity to all 

three types of polioviruses. This is part of a transition to withdraw all OPV from the world. After 

the switch, IPV will provide protection against paralysis from Type 2 polioviruses and boost 

immunity against Types 1 and 3. In previous OPV2 recipients, IPV will boost intestinal immunity 

to infections with Type 2 polioviruses. There was strategic use of IPV in response to Type 2 

poliovirus outbreaks alongside monovalent OPV2 (mOPV2) mass campaigns to increase 

population protection from paralysis. 

In terms of the results, there were fewer cVDPVs in 2016 than in over a decade. There was a 

Type 1 cVDPV outbreak on the island of Hispaniola. There was a predominance during the 

period of time from 2000-2016 of cVDPV2, which peaked in 2009. The majority of these were 

occurring in Nigeria. The switch occurred in 2016, at which time a nadir of cVDPV was reached.

Then, some bad news ensued. After reaching that nadir in 2016, the number of cVDPV2 cases 

and outbreaks increased dramatically. This represented an unprecedented phenomenon that 

had to be dealt with. Several outbreaks have been terminated after successful implementation 

of at least two mOPV2 rounds. However, many responses required over 4 rounds of mOPV2 to 

stop outbreaks. Many new emergences are occurring across the African region due to low 

quality responses with mOPV2. This is characterized by many countries with weak 

immunization systems, low routine immunization coverage, and low population immunity against 

the Type 2 virus as a result. Increasingly, outbreaks are occurring in areas where mOPV2 has 

not been used in a mass campaign. These outbreaks tend to occur in low-performing countries 

around the edges just outside the targeted geographic area for the OPV2 mass campaigns. 

These outbreaks are being caused by decreasing population mucosal and systemic immunity 

since OPV2 was withdrawn in 2016 and through population movement from the geographic 

areas where mOPV2 is being used to areas adjacent to that where it was not used.

Thus, there is an evolving new challenge that has never been faced previously. The program is 

battling many outbreaks of cVDPV2 in Sub-Saharan Africa, and is at risk of re-establishing 

poliovirus Type 2 endemicity in Africa with the cVDPV-derived virus. There is now detection of 

cVDPV2 outbreaks in Asia in China, Pakistan, and the Philippines that may herald a global 

emerging problem. There is a limited supply of global mOPV2 in the stockpile, which requires 

balancing its use with the availability of new shipments and the need for more production.

Dr. Cochi shared an article published last Fall by Helen Branswell, a well-known journalist and 

science writer who has followed the polio eradication situation for many years. The article was 

titled, ‘The Switch’ was supposed to be a major step toward eradicating polio. Now it’s a 

quandary. He pointed out that the dictionary definition of “quandary” is “a state of perplexity or 

uncertainty over what to do in a difficult situation.” In terms of where to go from here, efforts are 

being made to improve the quality of mOPV2 campaigns by more rapid deployment of mOPV2

supplies, revised strategy guidance for control of cVDPV2 that is more aggressive (finalized in 

January 2020), and increased scope and quality of mOPV2 of mass campaigns with a surge in 
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technical support. Work is also underway to accelerate the development and regulatory review 

and use of novel OPV2 through the Emergency Use Listing (EUL). 

mOPV2 is a genetic modification of the existing OPV2. For the past several years, the Gates 

Foundation has invested heavily in the development of this new vaccine, as well as nOPV1 and 

nOPV3 that are not as far along in the development stage. The two candidate vaccines have 

multiple changes in the genome on the 5’ and 3’ ends. One of the vaccines also has multiple 

changes in the nucleotide sequence in the P1 region, which is the capsular protein. The belief is 

that these re-designed vaccines will decrease the risk of seeding new cVDPVs and the risk of 

VAPP when deployed under cVDPV2 outbreak control circumstances.

The regulatory approval process for this new vaccine is being accelerated through an EUL. The 

owner of the EUL is the WHO Essential Medicine Department (EMP). The goal is to make 

“experimental” health products available for emergency response. The EUL is very new and as 

such, no products have been listed under the EUL thus far. The eligibility criteria for an EUL is 

that it has to be a product that deals with controlling the spread of a disease that already has 

been deemed a Public Health Emergency of International Concern (PHEIC), which falls under 

the International Health Regulations (IHRs) governed by the WHO. Coronavirus recently has 

been declared a PHEIC. There are very few such instances in which this has been used. This is 

the fastest way to obtain regulatory review and approval. 

Dr. Cochi briefly described the process that will be necessary for ramp-up of nOPV2 clinical 

development and production to align with EUL approval. Many studies already have been 

conducted in adults, and more recently in children, to develop the database on immunogenicity 

and safety and shedding of these viruses in children 1 to 5 years of age. Genetic stability 

already has occurred in adults and is in the process of being studied in young children. A pilot 

production scale facility in Indonesia has been identified. The WHO process is anticipated to 

take the next 3 months. During that period of time, approximately 4 to 8 million pilot doses of 

vaccine are being developed by the Indonesia manufacturer. Further studies will then be 

conducted on the genetic stability, updated stability data, and further examination of the 

production facility on a commercial scale through a 1-month review. By July to August of 2020, 

the hope is to have 100 million doses commercially available for use in the field. By the end of 

the 2020, another 100 million doses are anticipated to be ready for commercial availability/use. 

It is anticipated that these 200 million doses of vaccine will be utilized in a transition period as a 

replacement for the current mOPV2.

In summary, polio eradication made some progress in 2019, but encountered serious 

challenges. WPV eradication requires access in Afghanistan and vaccination quality 

improvements and accountability in Pakistan. Several cVDPV2 outbreaks threaten the success 

of “the switch” and may lead to re-establishment of Type 2 endemicity. mOPV2 needs to be 

replaced as soon as feasible by nOPV2, which is more stable genetically. A second dose of IPV 

in routine immunization is under discussion when supplies allow. It is anticipated that supplies 

will grow with entering into the market of a number of developing country manufacturers, so this 

could take place in the near future. Securing the funds to run the program is a very high priority, 

and has been emphasized by having to respond to all of these VDPV outbreaks.
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Discussion Points

Dr. Jean Smith indicated that she retired from CDC in 2018. She said she was fortunate for 

CDC to secund her to WHO in India, Nepal, and the Southeast Asia Region from 1995-2005 

thanks to Dr. Cochi. She requested that Dr. Cochi say something about the situation in VAPP in 

countries still using OPV, whether the incidence is known, and the awareness and reaction if 

there is VAPP in these countries.

Dr. Cochi replied that there continues to be VAPP in the OVP-using countries. However, it is 

very difficult to define what is/is not a VAPP case in these developing country situations 

because they do not have the technology available like industrialized countries such as the US 

has to make those distinctions. The incidence of VAPP has decreased substantially, given that 

the OPV2 that was causing about 90% of all of the DVPD cases was responsible for about 40% 

overall of all of the VAPP cases. In a general sense, it can be said that the incidence of VAPP is 

down. However, the goal is for the incidence of VAPP to go to 0 by withdrawing all OPV, 

including the use of bivalent OPV (bOPV). The problems with the cVDPVs outbreaks have 

delayed the transition toward an all-IPV future.

Sharon Frey, MD

Chair, Hepatitis Vaccines Work Group 

Saint Louis University Medical School

Dr. Frey indicated that the Hepatitis B Work Group (WG) is continuing its work. The current term 

of reference for this group is to update the recommendations for hepatitis B vaccination among 

US adults. The current recommendations for hepatitis B have been updated twice since 2008. 

This included new recommendations plus several updates, as well as the recommendation for 

use for adjuvanted Hepatitis B vaccine:

 Recommendations of the Advisory Committee on Immunization Practices for Use of a 

Hepatitis B Vaccine with a Novel Adjuvant. MMWR April 20, 2018;67:455–458.

 Prevention of Hepatitis B Virus Infection in the United States: Recommendations of the 

Advisory Committee on Immunization Practices. MMWR, January 12, 2018;67(No. RR-1):1–

31. 

The WG has been busy. From September 2019 through November 2019, the WG developed a 

PICO question and estimated denominators of risk groups. In January 2020, the WG gave a 

presentation of interim results of a post-marketing surveillance study that was done by the 

Principal Investigator (PI) at Kaiser Permanent Southern California (KPSC). The WG discussion 

in Spring 2020 will include discussion of the cost-effectiveness analysis (CEA), which is 

currently under ACIP technical review in an external WG.

Hepatitis B Vaccines
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The policy question under discussion for the next round is, “Should a routine universal HepBvaccination strategy (2-dose and 3-dose schedules) be utilized vs. the current risk-based 

vaccination strategy (2-dose and 3-dose) for adults?” The outcomes of interest include: 

Mortality, Morbidity, Incidence, Vaccine Uptake, Seroprotection, and Adverse Events (Mild and 

Serious). 

The next steps are to continue deliberations on updates to adult hepatitis B vaccination. That 

will include completion of the CEA review process and presentation of the CEA to the WG; 

discussion of the final results of the post-marketing surveillance study for HEPLISAV-B®, when 

available; and initiation of the Grading of Recommendation Assessment, Development, and 

Evaluation (GRADE) and Evaluation to Recommendation (EtR) framework for universal adult 

hepatitis B vaccination. 

Overview

Paul Hunter, MD

Chair, ACIP General Best Practices Work Group

Associate Professor of Family Medicine and Community Health

University of Wisconsin School of Medicine and Public Health

Associate Medical Director, City of Milwaukee Health Department

Dr. Hunter noted that he is the outgoing Chair for the Best Practices WG and that Dr. Bahta is 

the incoming Chair and Dr. Sanchez is the other ACIP member serving on the WG.

The terms of reference for the General Best Practices WG are to: 1) Revise the ACIP General 

Best Practice Guidelines for Immunization. The last revision was in 2019, sections of which are 

to be revised every two years; 2) Address issues related to general best practices for vaccines 

and immunization programs; and 3) Work on emergent issues that do not clearly belong to 

another specific pre-existing WG. 

The adult and child adolescent schedules summarize the ACIP vaccine-specific 

recommendations for implementing those recommendations in clinical and public health 

practice. The General Best Practice Guidelines for Immunizations help clinicians, nurses, 

pharmacists, and other vaccinators answer practical questions that are not or cannot be directly 

addressed by vaccine-specific recommendations.

The General Best Practice Guidelines for Immunizations are CDC guidance with input from the 

WG. Major changes require discussion by the ACIP, but rarely would this require a vote. 

Updates are uploaded to the ACIP website on a rolling schedule, primarily in order to maintain 

accreditation for continuing education credit.

General Best Practices
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Update on Recent Postings

Andrew Kroger, MD MPH

Medical Officer

National Center for Immunization and Respiratory Diseases

Centers for Disease Control and Prevention

Dr. Kroger pointed out that this informational session would complete a loop with ACIP that 

began during the October 2018 meeting involving content that was added to the General Best 

Practice Guidelines for Immunizations, as well as supply additional updates that have been 

posted in the past year that represent harmonizing with voted, cleared ACIP recommendations.

On the landing page for the HTML versions of the General Best Practice Guidelines for

Immunizations documents, each of the light gray banners in the center of the page represents a 

separate listing of all of the general topics: 

 Introduction

 Methods 

 Timing and Spacing of Immunobiologics

 Contraindications and Precautions

 Preventing and Managing Adverse Reactions

 Reporting Adverse Events After Vaccination 

 Vaccine Administration

 Storage and Handling of Immunobiologics

 Altered Immunocompetence

 Special Situations

 Vaccination Records

 Vaccination Programs 

 Vaccine Information Sources

On the right side of the landing page is the link for information on how to obtain continuing 

education credit. The most recent renewing of the credit was in April 2019. That followed the 

October 2018 discussion. The new cover page reflects the new authorship, with Dr. Kroger and 

all of the ACIP Chairs of the General Best Practices WG since the previous revision of the 

document in 2017. One can access the PDF of the entire document or individual PDFs of all of 

the separate chapters. Because revisions occur constantly to this on-line document, it is not 

likely that a PDF of the entire document will remain timely for long.

Each revision is indexed by the date, in order of the most recent changes, with links to the 

appropriate areas of the document. Under May 14, 2019, Dr. Kroger inserted a notification that 

an entire section of the document, Vaccination Administration, was revised following the 

focused ACIP discussion and the clearance of the section through CDC eClearance. This is the 

section that was discussed and now added to the document. It reads: 
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Health Care Provider Exposure to Vaccine Components

Providers are sometimes concerned when they have the same contraindications or 

precautions as their patients from whom they withhold or defer vaccine. For 

administration of routinely recommended vaccines, there is no evidence of risk of 

exposure of vaccine components to the health care provider, so conditions in the 

provider labeled as contraindications and precautions to vaccine components are not a 

reason to withdraw from this function of administering the vaccine to someone else. 

Historic concerns about exposure to vaccine components are limited to non-parenteral 

vaccines in which some degree of environmental exposure is unavoidable (5, 6), or 

situations in which self-inoculation is likely due to the nature of the vaccine microbe [e.g. 

reduced attenuation of smallpox vaccine virus (7)]. Persons administering ACAM 2000 

smallpox vaccine to laboratory and health care personnel at risk for occupational 

exposure to orthopoxviruses can decrease the risk for inadvertent infection through 

recommended infection prevention measures. However, because of a theoretical risk for 

infection, vaccination with ACAM2000 can be offered to health care personnel 

administering this vaccine, provided individual persons have no specified 

contraindications to vaccination (8).

There have been 6 other updates since October 2018 to the on-line document, which reflect 

harmonization with existing CDC content. It is important to note that all of this is content that is 

already in an MMWR vaccine-specific statement, so none of this is new. The first is the addition 

of the 2-dose series of HPV vaccine, which was added to the Timing and Spacing interval table. 

It accompanies the 3-dose series, which remains on the table. Also in Timing and Spacing, HIV 

was added to conditions for which PREVNAR 13® and Menactra® should be spaced by 4 

weeks. Providers are recommended to administer PREVNAR 13® and then Menactra® 4 weeks 

later. There are three additions to the Contraindications and Precautions section. One is that an 

exception was carved out for recombinant zoster vaccine. There is no need for an interval 

between recombinant zoster vaccine and anti-herpes antivirals. This is a non-live vaccine, so 

the concern about interference does not exist with recombinant zoster vaccine.

Some changes were made to some of the listings in the table because of components that were 

identified. Yeast is acknowledged as a component of PCV13, which is relevant when discussing 

allergies. Pregnancy was added as a reason not to administer HPV vaccine. The language that 

states that “HPV vaccine is not recommended in pregnancy” follows the removal of HPV 

vaccine as a column listing for Precautions because pregnancy is not a precaution to HPV 

vaccine. It is that HPV vaccine is not recommended in pregnancy. The last change is under 

Storage and Handling. Content was removed from the previous published MMWR version of the 

General Best Practices regarding information about when to repeat doses of vaccine that are 

administered and then later found to be expired. This information had to be added back in. 

There are some interesting nuances here. Non-live vaccines generally would not require an 

interval from the vaccine that is invalidated because it is expired. The dose would just be 

repeated as soon as possible. The exception to that is SHINGRIX, which is not live but does 

require a 4-week interval because of safety considerations.
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Dr. Jeanne M. Santoli

Immunization Services Division

National Center for Immunization and Respiratory Diseases

Centers for Disease Control and Prevention

During this session, Dr. Santoli presented an update on the pediatric and adult HepB vaccine 

supply. She reported that Merck will begin distributing its pediatric monovalent HepB vaccine in 

the private sector effective March 9, 2020. As a reminder, Merck’s limited supply previously was

targeted toward the public sector using CDC’s vaccine contracts. Now it will be available in the 

private sector as well. In addition, Merck projects that its available supply of monovalent vaccine 

will be sufficient to meet historical demand for this vaccine in both the public and private sectors.

Merck will not be distributing its adult HepB vaccine or the dialysis formulation through at least 

the first half of 2020. Dynavax and GSK have sufficient supplies of adult HepB vaccines to 

address the anticipated gap in Merck’s adult HepB vaccine supply during this period. However, 

preference for a specific presentation (i.e., vial versus syringe) may not be met uniformly during 

this time.

As a reminder, CDC has a vaccine supply page that is kept updated in sync with all of the 

updates made during ACIP meetings. The Vaccine Supply/Shortage Webpage can be found at:

https://www.cdc.gov/vaccines/hcp/clinical-resources/shortages.html.

Discussion Points

Dr. Hunter requested clarity that the Merck adult HepB vaccine shortage was not new. 

Dr. Santoli clarified that the shortage has been ongoing for a couple of years. What is new 

information is that in October 2019, she reported that there would not be distribution through the 

end of 2020, but Merck is now saying it will not be distributing its adult HepB vaccine or dialysis 

formulation through the first half of 2020. That foreshadows what is to come and they are hoping 

to have another update the next time they talk.

Vaccine Supply
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Upon reviewing the foregoing version of the February 26-27, 2020 ACIP meeting minutes, Dr. 

Jose Romero, ACIP Chair, certified that to the best of his knowledge, they are accurate and 

complete. His original, signed certification is on file with the Management Analysis and Services 

Office (MASO) of CDC.

Certification
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October 2019

Department of Health and Human Services 

Centers for Disease Control and Prevention 

Advisory Committee on Immunization Practices 

July 1, 2019 – June 30, 2020 

 

CHAIR 

ROMERO, José R., MD, FAAP 

Professor of Pediatrics 

Horace C. Cabe Endowed Chair in Infectious Diseases Director, 

Pediatric Infectious Diseases Section 

University of Arkansas for Medical Sciences and Arkansas Children's Hospital 

Director, Clinical Trials Research 

Arkansas Children's Hospital Research Institute 

Little Rock, AR 

Term: 10/30/2018-06/30/2021 

 

EXECUTIVE SECRETARY

COHN, Amanda, MD 

Senior Advisor for Vaccines 

National Center for Immunization and Respiratory Diseases 

Centers for Disease Control and Prevention 

Atlanta, GA 

 

MEMBERS 

ATMAR, Robert L., MD 

John S. Dunn Clinical Research Professor in Infectious Diseases 

Departments of Medicine and Molecular Virology & Microbiology 

Baylor College of Medicine 

Chief, Infectious Diseases Service 

Ben Taub General Hospital, Harris Health System

Houston, TX 

Term: 7/1/2016 – 6/30/2020 

AULT, Kevin A., MD, FACOG, FIDSA 

Professor and Division Director 

Department of Obstetrics and Gynecology 

University of Kansas Medical Center

Kansas City, KS 

Term: 10/26/2018 – 6/30/2022 

 

BAHTA, Lynn, RN, MPH, CPH 

Immunization Program Clinical Consultant 

Infectious Disease, Epidemiology, Prevention & Control Division 

Minnesota Department of Health 

Saint Paul, Minnesota 

Term: 7/1/2019 – 6/30/2023 

ACIP Membership Roster
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BELL, Beth P., MD, MPH 

Clinical Professor 

Department of Global Health, School of Public Health 

University of Washington 

Seattle, WA 

Term: 7/1/2019 – 6/30/2023 

BERNSTEIN, Henry, DO, MHCM, FAAP 

Professor of Pediatrics 

Zucker School of Medicine at Hofstra/Northwell 

Cohen Children’s Medical Center 

New Hyde Park, NY 

Term: 11/27/2017-06/30/2021 

 

FREY, Sharon E., M.D. 

Professor and Associate Director of Clinical Research 

Clinical Director, Center for Vaccine Development 

Division of Infectious Diseases, Allergy and Immunology 

Saint Louis University Medical School 

Saint Louis, MO 

Term: 11/27/2017-06/30/2021 

 

HUNTER, Paul, MD 

Associate Professor of Family Medicine and Community Health 

University of Wisconsin School of Medicine and Public Health 

Associate Medical Director 

City of Milwaukee Health Department 

Milwaukee, WI 

Term: 7/1/2016 – 6/30/2020 

 

LEE, Grace M., MD, MPH 

Associate Chief Medical Officer for Practice Innovation 

Lucile Packard Children’s Hospital 

Professor of Pediatrics, Stanford University School of Medicine 

Stanford, CA 

Term: 7/1/2016 – 6/30/2020 

 

MCNALLY, Veronica V., JD 

President and CEO Franny 

Strong Foundation 

West Bloomfield, Michigan 

Term: 10/31/2018 – 6/30/2022 

 

POEHLING, Katherine A., MD, MPH 

Professor of Pediatrics and Epidemiology and Prevention Director, 

Pediatric Population Health 

Department of Pediatrics 

Wake Forest School of Medicine 

Winston-Salem, NC 

Term: 7/1/2019 – 6/30/2023 
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Pablo J. Sánchez, M.D. 

Professor of Pediatrics 

The Ohio State University – Nationwide Children’s Hospital 

Divisions of Neonatal-Perinatal Medicine and Pediatric Infectious Diseases 

Director, Clinical & Translational Research (Neonatology) 

Center for Perinatal Research 

The Research Institute at Nationwide Children's Hospital 

Columbus, Ohio

Term: 7/1/2019 – 6/30/2023 

 

SZILAGYI, Peter, MD, MPH 

Professor of Pediatrics 

Executive Vice-Chair and Vice-Chair for Research 

Department of Pediatrics 

University of California, Los Angeles (UCLA) 

Los Angeles, California 

Term: 7/1/2016 – 6/30/2020 

 

TALBOT, Helen Keipp, MD 

Associate Professor of Medicine 

Vanderbilt University

Nashville, TN 

Term: 10/29/2018 – 6/30/2022 

 

EX OFFICIO MEMBERS 

Centers for Medicare and Medicaid Services (CMS) 

HANCE, Mary Beth 

Senior Policy Advisor 

Division of Quality, Evaluations and Health Outcomes 

Children and Adults Health Programs Group 

Center for Medicaid, CHIP and Survey & Certification 

Centers for Medicare and Medicaid Services 

Baltimore, MD 

 

Department of Defense (DoD) 

DEUSSING, ERIC, MD, MPH 

Commander, Medical Corps, United States Navy 

Department of Defense Liaison 

Centers for Disease Control and Prevention 

Atlanta, GA 

Department of Veterans Affairs (DVA) 

KIM, Jane A., MD, MPH 

Deputy Chief Consultant for Preventive Medicine 

Office of Patient Care Services 

National Center for Health Promotion and Disease Prevention 

Durham, North Carolina 

 
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Food and Drug Administration (FDA) 

FINK, Doran, MD, PhD 

Deputy Director, Clinical, Division of Vaccines and Related Products Applications 

Office of Vaccines Research and Review 

Center for Biologics Evaluation and Research 

Food and Drug Administration Silver 

Spring, MD 

 

Health Resources and Services Administration (HRSA) 

 

Indian Health Service (IHS) 

WEISER, Thomas, MD, MPH 

Medical Epidemiologist 

Portland Area Indian Health Service 

Portland, OR 

 

Office of Infectious Disease and HIV/AIDS Policy (OIDP) 

BECKHAM, Tammy 

Acting Director 

 

National Institutes of Health (NIH) 

BEIGEL, John, M.D. 

Associate Director for Clinical Research 

Division of Microbiology and Infectious Diseases 

National Institute of Allergy and Infectious Diseases (NIAID) Bethesda, MD 

 

LIAISON REPRESENTATIVES 

American Academy of Family Physicians (AAFP) 

ROCKWELL, Pamela G., D.O. 

Associate Professor, Department of Family Medicine, 

University of Michigan Medical School 

Medical Director, Dominos Farms Family Medicine Ann 

Arbor, MI 

 

American Academy of Pediatrics (AAP) 

MALDONADO, Yvonne, MD 

Senior Associate Dean for Faculty Development and Diversity 

Professor of Pediatrics and Health Research and Policy 

Chief, Division of Pediatric Infectious Diseases 

Stanford University School of Medicine 

Stanford, CA 

 

American Academy of Pediatrics (AAP) 

Red Book Editor KIMBERLIN, 

David, MD 

Professor of Pediatrics 

Division of Pediatric Infectious Diseases 

The University of Alabama at Birmingham School of Medicine

Birmingham, AL 
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American Academy of Physician Assistants (AAPA) 

LÉGER, Marie-Michèle, MPH, PA-C Senior 

Director, Clinical and Health Affairs 

American Academy of Physician Assistants

Alexandria, VA 

American College Health Association (ACHA) 

EVEN, Susan, MD 

Executive Director 

Student Health Center 

University of Missouri 

Columbia, MO 

American College of Nurse Midwives (ACNM) 

HAYES, Carol E., CNM, MN, MPH Lead 

Clinician 

Clinical Quality Compliance and Management 

Planned Parenthood Southeast 

Atlanta, GA 

American College of Nurse Midwives (ACNM) (alternate) 

MEHARRY, Pamela M., PHD, CNM 

Midwifery Educator, Human Resources for Health 

In partnership with University of Rwanda and University of Illinois, Chicago 

American College of Obstetricians and Gynecologists (ACOG) 

ECKERT, Linda O., MD, FACOG 

Professor, Department of Obstetrics & Gynecology 

Adjunct Professor, Department of Global Health 

University of Washington 

Seattle, WA 

American College of Physicians (ACP) 

GOLDMAN, Jason M. MD, FACP 

Affiliate Assistant Professor of Clinical Biomedical Science, Florida Atlantic 

University, Boca Raton, Florida 

Private Practice 

Coral Springs, FL 

American Geriatrics Society (AGS) 

SCHMADER, Kenneth, MD 

Professor of Medicine-Geriatrics 

Geriatrics Division Chief 

Duke University and Durham VA Medical Centers

Durham, NC 

America’s Health Insurance Plans (AHIP) 

Vacant
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American Immunization Registry Association (AIRA) 

COYLE, Rebecca, MSEd 

Executive Director, AIRA

Washington, DC 

 

American Medical Association (AMA) 

FRYHOFER, Sandra Adamson, MD 

Adjunct Associate Professor of Medicine 

Emory University School of Medicine

Atlanta, GA 

 

American Nurses Association (ANA) 

RITTLE, Charles (Chad), DNP, MPH, RN 

Assistant Professor, Nursing Faculty 

Chatham University, School of Health Sciences

Pittsburgh, PA 

 

American Osteopathic Association (AOA) 

GROGG, Stanley E., DO 

Associate Dean/Professor of Pediatrics 

Oklahoma State University-Center for Health Sciences 

Tulsa, OK 

American Pharmacists Association (APhA) 

FOSTER, Stephan L., PharmD CAPT (Ret) 

U.S.P.H.S. 

Professor, College of Pharmacy 

University of Tennessee Health Sciences Center 

Memphis, TN 

Association of Immunization Managers (AIM) 

FINLEY, Christine, RN, MPH 

Immunization Program Manager 

Vermont Department of Health 

Burlington, VT 

 

Association for Prevention Teaching and Research (APTR) 

McKINNEY, W. Paul, MD 

Professor and Associate Dean 

University of Louisville School of Public Health and Information Sciences

Louisville, KY 

Association of State and Territorial Health Officials (ASTHO) 

SMITH, Nathaniel, MD, MPH 

Director and State Health Officer 

Arkansas Department of Health Little 

Rock, AR 
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Biotechnology Industry Organization (BIO) 

ARTHUR, Phyllis A., MBA 

Senior Director, Vaccines, Immunotherapeutics and Diagnostics Policy 

Washington, DC

Council of State and Territorial Epidemiologists (CSTE) 

HAHN, Christine, MD State 

Epidemiologist 

Office of Epidemiology, Food Protection and Immunization Idaho 

Department of Health and Welfare

Boise, ID 

 

Council of State and Territorial Epidemiologists (CSTE)

(alternate) LETT, Susan, MD, MPH 

Medical Director, Immunization Program 

Division of Epidemiology and Immunization 

Massachusetts Department of Public Health 

Boston, MA 

 

Canadian National Advisory Committee on Immunization (NACI) 

QUACH, Caroline, MD, MSc 

Pediatric Infectious Disease Specialist and Medical Microbiologist 

Medical Lead, Infection Prevention and Control Unit 

Medical Co-director – Laboratory Medicine, Optilab 

Montreal-CHUM 

Montreal, Québec, Canada 

 

Infectious Diseases Society of America (IDSA) 

BAKER, Carol J., MD 

Professor of Pediatrics 

Molecular Virology and Microbiology 

Baylor College of Medicine

Houston, TX 

 

National Association of County and City Health Officials (NACCHO) 

ZAHN, Matthew, MD 

Medical Director, Epidemiology 

Orange County Health Care Agency Santa 

Ana, CA 

 

National Association of County and City Health Officials (NACCHO)

(alternate) DUCHIN, Jeffrey, MD 

Health Officer and Chief, Communicable Disease Epidemiology and Immunization 

Section 

Public Health - Seattle and King County 

Professor in Medicine 

Division of Allergy and Infectious Diseases 

University of Washington School of Medicine and School of Public Health

Seattle, WA
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National Association of Pediatric Nurse Practitioners (NAPNAP) 

STINCHFIELD, Patricia A., RN, MS, CPNP 

Director, Infectious Disease/Immunology/Infection Control 

Children's Hospitals and Clinics of Minnesota

St. Paul, MN 

 

National Foundation for Infectious Diseases (NFID) 

SCHAFFNER, William, MD 

Chairman, Department of Preventive Medicine 

Vanderbilt University School of Medicine 

Nashville, TN 

National Immunization Council and Child Health Program, Mexico 

DURAN, Luis, MD 

Director, Center for Children and Adolescent Health (CeNSIA) 

Ministry of Health / Secretaría de Salud 

Mexico 

 

National Medical Association (NMA) 

WHITLEY-WILLIAMS, Patricia, MD 

Professor and Chair 

University of Medicine and Dentistry of New Jersey 

Robert Wood Johnson Medical School 

New Brunswick, NJ 

 

Pediatric Infectious Diseases Society (PIDS) 

O’LEARY, Sean, MD, MPH 

Associate Professor of Pediatrics 

Pediatric Infectious Diseases 

General Academic Pediatrics 

Children’s Hospital Colorado 

University of Colorado School of Medicine 

 

Pediatric Infectious Diseases Society (PIDS)

(alternate) SAWYER, Mark H, MD 

Professor of Clinical Pediatrics 

University of California, San Diego School of Medicine 

San Diego, CA 

 

Pharmaceutical Research and Manufacturers of America (PhRMA) 

ROBERTSON, Corey, MD, MPH 

Senior Director, US Medical, Sanofi Pasteur

Swiftwater, PA 

 

Society for Adolescent Health and Medicine (SAHM) 

MIDDLEMAN, Amy B., MD, MSEd, MPH 

Professor of Pediatrics 

Chief, Section of Adolescent Medicine 

University of Oklahoma Health Sciences Center 

Oklahoma City, OK 
Advisory Committee on Immunization Practices (ACIP) Summary Report February 26-27, 2020

137

Society for Healthcare Epidemiology of America (SHEA) 

WEBER, David, MD, MPH 

Professor of Medicine, Pediatrics, and Epidemiology 

University of North Carolina Schools of Medicine and Public Health 

Medical Director, Hospital Epidemiology and Occupational Health, UNC Health Care 

University of North Carolina 

Chapel Hill, NC